diff --git a/.coveragerc b/.coveragerc
index d097511c..34417c3f 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -11,3 +11,5 @@ exclude_lines =
     def __repr__
     # Ignore abstract methods
     raise NotImplementedError
+    # Ignore coverage for code specific to static type checkers
+    TYPE_CHECKING
diff --git a/.github/.OwlBot.lock.yaml b/.github/.OwlBot.lock.yaml
index b771c37c..51b21a62 100644
--- a/.github/.OwlBot.lock.yaml
+++ b/.github/.OwlBot.lock.yaml
@@ -1,3 +1,17 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
 docker:
-  image: gcr.io/repo-automation-bots/owlbot-python:latest
-  digest: sha256:a1a891041baa4ffbe1a809ac1b8b9b4a71887293c9101c88e8e255943c5aec2d
+  image: gcr.io/cloud-devrel-public-resources/owlbot-python:latest
+  digest: sha256:a7aef70df5f13313ddc027409fc8f3151422ec2a57ac8730fce8fa75c060d5bb
+# created: 2025-04-10T17:00:10.042601326Z
diff --git a/.github/.OwlBot.yaml b/.github/.OwlBot.yaml
index 3caf68d4..c8b40cc7 100644
--- a/.github/.OwlBot.yaml
+++ b/.github/.OwlBot.yaml
@@ -13,7 +13,7 @@
 # limitations under the License.
 
 docker:
-  image: gcr.io/repo-automation-bots/owlbot-python:latest
+  image: gcr.io/cloud-devrel-public-resources/owlbot-python:latest
 
 begin-after-commit-hash: 7af2cb8b2b725641ac0d07e2f256d453682802e6
 
diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index 557e39e1..1b023b72 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -3,9 +3,10 @@
 #
 # For syntax help see:
 # https://help.github.com/en/github/creating-cloning-and-archiving-repositories/about-code-owners#codeowners-syntax
+# Note: This file is autogenerated. To make changes to the codeowner team, please update .repo-metadata.json.
 
-# The @googleapis/yoshi-python is the default owner for changes in this repo
-*               @googleapis/yoshi-python @googleapis/actools-python
+# @googleapis/yoshi-python @googleapis/actools-python are the default owners for changes in this repo
+*     @googleapis/yoshi-python @googleapis/actools-python
 
-# The python-samples-reviewers team is the default owner for samples changes
-/samples/  @googleapis/python-samples-owners
+# @googleapis/python-samples-reviewers @googleapis/actools-python are the default owners for samples changes
+/samples/   @googleapis/python-samples-reviewers @googleapis/actools-python
diff --git a/.github/auto-approve.yml b/.github/auto-approve.yml
new file mode 100644
index 00000000..311ebbb8
--- /dev/null
+++ b/.github/auto-approve.yml
@@ -0,0 +1,3 @@
+# https://github.com/googleapis/repo-automation-bots/tree/main/packages/auto-approve
+processes:
+  - "OwlBotTemplateChanges"
diff --git a/google/__init__.py b/.github/auto-label.yaml
similarity index 70%
rename from google/__init__.py
rename to .github/auto-label.yaml
index 0d0a4c3a..21786a4e 100644
--- a/google/__init__.py
+++ b/.github/auto-label.yaml
@@ -1,4 +1,4 @@
-# Copyright 2016 Google LLC
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -11,14 +11,10 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+requestsize:
+  enabled: true
 
-"""Google namespace package."""
-
-try:
-    import pkg_resources
-
-    pkg_resources.declare_namespace(__name__)
-except ImportError:
-    import pkgutil
-
-    __path__ = pkgutil.extend_path(__path__, __name__)
+path:
+  pullrequest: true
+  paths:
+    samples: "samples"
diff --git a/.github/blunderbuss.yml b/.github/blunderbuss.yml
new file mode 100644
index 00000000..1618464d
--- /dev/null
+++ b/.github/blunderbuss.yml
@@ -0,0 +1,17 @@
+# Blunderbuss config
+#
+# This file controls who is assigned for pull requests and issues.
+# Note: This file is autogenerated. To make changes to the assignee
+# team, please update `codeowner_team` in `.repo-metadata.json`.
+assign_issues:
+  - googleapis/actools-python
+
+assign_issues_by:
+  - labels:
+      - "samples"
+    to:
+      - googleapis/python-samples-reviewers
+      - googleapis/actools-python
+
+assign_prs:
+  - googleapis/actools-python
diff --git a/.github/cherry-pick-bot.yml b/.github/cherry-pick-bot.yml
new file mode 100644
index 00000000..1e9cfcd3
--- /dev/null
+++ b/.github/cherry-pick-bot.yml
@@ -0,0 +1,2 @@
+enabled: true
+
diff --git a/.github/release-please.yml b/.github/release-please.yml
index 4507ad05..29601ad4 100644
--- a/.github/release-please.yml
+++ b/.github/release-please.yml
@@ -1 +1,11 @@
 releaseType: python
+handleGHRelease: true
+# NOTE: this section is generated by synthtool.languages.python
+# See https://github.com/googleapis/synthtool/blob/master/synthtool/languages/python.py
+branches:
+- branch: v1
+  handleGHRelease: true
+  releaseType: python
+- branch: v0
+  handleGHRelease: true
+  releaseType: python
diff --git a/.github/release-trigger.yml b/.github/release-trigger.yml
new file mode 100644
index 00000000..50e8bd30
--- /dev/null
+++ b/.github/release-trigger.yml
@@ -0,0 +1,2 @@
+enabled: true
+multiScmName: python-api-core
diff --git a/.github/sync-repo-settings.yaml b/.github/sync-repo-settings.yaml
index e621885d..b724bada 100644
--- a/.github/sync-repo-settings.yaml
+++ b/.github/sync-repo-settings.yaml
@@ -1,3 +1,56 @@
+# https://github.com/googleapis/repo-automation-bots/tree/main/packages/sync-repo-settings
+# Rules for main branch protection
+branchProtectionRules:
+# Identifies the protection rule pattern. Name of the branch to be protected.
+# Defaults to `main`
+- pattern: main
+  requiresCodeOwnerReviews: true
+  requiresStrictStatusChecks: true
+  requiredStatusCheckContexts:
+    - 'cla/google'
+    # No Kokoro:  the following are Github actions
+    - 'lint'
+    - 'mypy'
+    - 'unit_grpc_gcp-3.7'
+    - 'unit_grpc_gcp-3.8'
+    - 'unit_grpc_gcp-3.9'
+    - 'unit_grpc_gcp-3.10'
+    - 'unit_grpc_gcp-3.11'
+    - 'unit_grpc_gcp-3.12'
+    - 'unit_grpc_gcp-3.13'
+    - 'unit_grpc_gcp-3.14'
+    - 'unit-3.7'
+    - 'unit-3.8'
+    - 'unit-3.9'
+    - 'unit-3.10'
+    - 'unit-3.11'
+    - 'unit-3.12'
+    - 'unit-3.13'
+    - 'unit-3.14'
+    - 'unit_wo_grpc-3.10'
+    - 'unit_wo_grpc-3.11'
+    - 'unit_wo_grpc-3.12'
+    - 'unit_wo_grpc-3.13'
+    - 'unit_wo_grpc-3.14'
+    - 'unit_w_prerelease_deps-3.7'
+    - 'unit_w_prerelease_deps-3.8'
+    - 'unit_w_prerelease_deps-3.9'
+    - 'unit_w_prerelease_deps-3.10'
+    - 'unit_w_prerelease_deps-3.11'
+    - 'unit_w_prerelease_deps-3.12'
+    - 'unit_w_prerelease_deps-3.13'
+    - 'unit_w_prerelease_deps-3.14'
+    - 'unit_w_async_rest_extra-3.7'
+    - 'unit_w_async_rest_extra-3.8'
+    - 'unit_w_async_rest_extra-3.9'
+    - 'unit_w_async_rest_extra-3.10'
+    - 'unit_w_async_rest_extra-3.11'
+    - 'unit_w_async_rest_extra-3.12'
+    - 'unit_w_async_rest_extra-3.13'
+    - 'unit_w_async_rest_extra-3.14'
+    - 'cover'
+    - 'docs'
+    - 'docfx'
 permissionRules:
   - team: actools-python
     permission: admin
diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
new file mode 100644
index 00000000..2833fe98
--- /dev/null
+++ b/.github/workflows/docs.yml
@@ -0,0 +1,38 @@
+on:
+  pull_request:
+    branches:
+      - main
+name: docs
+jobs:
+  docs:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    - name: Setup Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: "3.10"
+    - name: Install nox
+      run: |
+        python -m pip install --upgrade setuptools pip wheel
+        python -m pip install nox
+    - name: Run docs
+      run: |
+        nox -s docs
+  docfx:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    - name: Setup Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: "3.10"
+    - name: Install nox
+      run: |
+        python -m pip install --upgrade setuptools pip wheel
+        python -m pip install nox
+    - name: Run docfx
+      run: |
+        nox -s docfx
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
new file mode 100644
index 00000000..1051da0b
--- /dev/null
+++ b/.github/workflows/lint.yml
@@ -0,0 +1,25 @@
+on:
+  pull_request:
+    branches:
+      - main
+name: lint
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    - name: Setup Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: "3.10"
+    - name: Install nox
+      run: |
+        python -m pip install --upgrade setuptools pip wheel
+        python -m pip install nox
+    - name: Run lint
+      run: |
+        nox -s lint
+    - name: Run lint_setup_py
+      run: |
+        nox -s lint_setup_py
diff --git a/.github/workflows/mypy.yml b/.github/workflows/mypy.yml
new file mode 100644
index 00000000..e6a79291
--- /dev/null
+++ b/.github/workflows/mypy.yml
@@ -0,0 +1,22 @@
+on:
+  pull_request:
+    branches:
+      - main
+name: mypy
+jobs:
+  mypy:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    - name: Setup Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: "3.10"
+    - name: Install nox
+      run: |
+        python -m pip install --upgrade setuptools pip wheel
+        python -m pip install nox
+    - name: Run mypy
+      run: |
+        nox -s mypy
diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
new file mode 100644
index 00000000..f260a6a5
--- /dev/null
+++ b/.github/workflows/unittest.yml
@@ -0,0 +1,82 @@
+name: "Unit tests"
+
+on:
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  run-unittests:
+    name: unit${{ matrix.option }}-${{ matrix.python }}
+    # TODO(https://github.com/googleapis/gapic-generator-python/issues/2303): use `ubuntu-latest` once this bug is fixed.
+    # Use ubuntu-22.04 until Python 3.7 is removed from the test matrix
+    # https://docs.github.com/en/actions/using-github-hosted-runners/using-github-hosted-runners/about-github-hosted-runners#standard-github-hosted-runners-for-public-repositories
+    runs-on: ubuntu-22.04
+    strategy:
+      matrix:
+        option: ["", "_grpc_gcp", "_wo_grpc", "_w_prerelease_deps", "_w_async_rest_extra"]
+        python:
+          - "3.7"
+          - "3.8"
+          - "3.9"
+          - "3.10"
+          - "3.11"
+          - "3.12"
+          - "3.13"
+          - "3.14"
+        exclude:
+          - option: "_wo_grpc"
+            python: 3.7
+          - option: "_wo_grpc"
+            python: 3.8
+          - option: "_wo_grpc"
+            python: 3.9
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    - name: Setup Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: ${{ matrix.python }}
+        allow-prereleases: true
+    - name: Install nox
+      run: |
+        python -m pip install --upgrade setuptools pip wheel
+        python -m pip install nox
+    - name: Run unit tests
+      env:
+        COVERAGE_FILE: .coverage${{ matrix.option }}-${{matrix.python }}
+      run: |
+        nox -s unit${{ matrix.option }}-${{ matrix.python }}
+    - name: Upload coverage results
+      uses: actions/upload-artifact@v4
+      with:
+        name: coverage-artifact-${{ matrix.option }}-${{ matrix.python }}
+        path: .coverage${{ matrix.option }}-${{ matrix.python }}
+        include-hidden-files: true
+
+  report-coverage:
+    name: cover
+    runs-on: ubuntu-latest
+    needs:
+        - run-unittests
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+    - name: Setup Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: "3.10"
+    - name: Install coverage
+      run: |
+        python -m pip install --upgrade setuptools pip wheel
+        python -m pip install coverage
+    - name: Download coverage results
+      uses: actions/download-artifact@v4
+      with:
+        path: .coverage-results/
+    - name: Report coverage results
+      run: |
+        find .coverage-results -type f -name '*.zip' -exec unzip {} \;
+        coverage combine .coverage-results/**/.coverage*
+        coverage report --show-missing --fail-under=100
diff --git a/.gitignore b/.gitignore
index 99c3a144..168b201f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -51,6 +51,7 @@ docs.metadata
 
 # Virtual environment
 env/
+venv/
 
 # Test logs
 coverage.xml
diff --git a/.kokoro/build.sh b/.kokoro/build.sh
index 8b9fd8a1..d41b45aa 100755
--- a/.kokoro/build.sh
+++ b/.kokoro/build.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2018 Google LLC
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -15,11 +15,13 @@
 
 set -eo pipefail
 
+CURRENT_DIR=$(dirname "${BASH_SOURCE[0]}")
+
 if [[ -z "${PROJECT_ROOT:-}" ]]; then
-    PROJECT_ROOT="github/python-api-core"
+  PROJECT_ROOT=$(realpath "${CURRENT_DIR}/..")
 fi
 
-cd "${PROJECT_ROOT}"
+pushd "${PROJECT_ROOT}"
 
 # Disable buffering, so that the logs stream through.
 export PYTHONUNBUFFERED=1
@@ -28,20 +30,19 @@ export PYTHONUNBUFFERED=1
 env | grep KOKORO
 
 # Setup service account credentials.
-export GOOGLE_APPLICATION_CREDENTIALS=${KOKORO_GFILE_DIR}/service-account.json
+if [[ -f "${KOKORO_GFILE_DIR}/service-account.json" ]]
+then
+  export GOOGLE_APPLICATION_CREDENTIALS=${KOKORO_GFILE_DIR}/service-account.json
+fi
 
 # Setup project id.
-export PROJECT_ID=$(cat "${KOKORO_GFILE_DIR}/project-id.json")
-
-# Remove old nox
-python3 -m pip uninstall --yes --quiet nox-automation
-
-# Install nox
-python3 -m pip install --upgrade --quiet nox
-python3 -m nox --version
+if [[ -f "${KOKORO_GFILE_DIR}/project-id.json" ]]
+then
+  export PROJECT_ID=$(cat "${KOKORO_GFILE_DIR}/project-id.json")
+fi
 
 # If this is a continuous build, send the test log to the FlakyBot.
-# See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
+# See https://github.com/googleapis/repo-automation-bots/tree/main/packages/flakybot.
 if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"continuous"* ]]; then
   cleanup() {
     chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
@@ -53,7 +54,7 @@ fi
 # If NOX_SESSION is set, it only runs the specified session,
 # otherwise run all the sessions.
 if [[ -n "${NOX_SESSION:-}" ]]; then
-    python3 -m nox -s ${NOX_SESSION:-}
+  python3 -m nox -s ${NOX_SESSION:-}
 else
-    python3 -m nox
+  python3 -m nox
 fi
diff --git a/.kokoro/continuous/prerelease-deps.cfg b/.kokoro/continuous/prerelease-deps.cfg
new file mode 100644
index 00000000..3595fb43
--- /dev/null
+++ b/.kokoro/continuous/prerelease-deps.cfg
@@ -0,0 +1,7 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Only run this nox session.
+env_vars: {
+    key: "NOX_SESSION"
+    value: "prerelease_deps"
+}
diff --git a/.kokoro/docker/docs/Dockerfile b/.kokoro/docker/docs/Dockerfile
deleted file mode 100644
index 4e1b1fb8..00000000
--- a/.kokoro/docker/docs/Dockerfile
+++ /dev/null
@@ -1,67 +0,0 @@
-# Copyright 2020 Google LLC
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-from ubuntu:20.04
-
-ENV DEBIAN_FRONTEND noninteractive
-
-# Ensure local Python is preferred over distribution Python.
-ENV PATH /usr/local/bin:$PATH
-
-# Install dependencies.
-RUN apt-get update \
-  && apt-get install -y --no-install-recommends \
-    apt-transport-https \
-    build-essential \
-    ca-certificates \
-    curl \
-    dirmngr \
-    git \
-    gpg-agent \
-    graphviz \
-    libbz2-dev \
-    libdb5.3-dev \
-    libexpat1-dev \
-    libffi-dev \
-    liblzma-dev \
-    libreadline-dev \
-    libsnappy-dev \
-    libssl-dev \
-    libsqlite3-dev \
-    portaudio19-dev \
-    python3-distutils \
-    redis-server \
-    software-properties-common \
-    ssh \
-    sudo \
-    tcl \
-    tcl-dev \
-    tk \
-    tk-dev \
-    uuid-dev \
-    wget \
-    zlib1g-dev \
-  && add-apt-repository universe \
-  && apt-get update \
-  && apt-get -y install jq \
-  && apt-get clean autoclean \
-  && apt-get autoremove -y \
-  && rm -rf /var/lib/apt/lists/* \
-  && rm -f /var/cache/apt/archives/*.deb
-
-RUN wget -O /tmp/get-pip.py 'https://bootstrap.pypa.io/get-pip.py' \
-  && python3.8 /tmp/get-pip.py \
-  && rm /tmp/get-pip.py
-
-CMD ["python3.8"]
diff --git a/.kokoro/docs/common.cfg b/.kokoro/docs/common.cfg
deleted file mode 100644
index 4847856f..00000000
--- a/.kokoro/docs/common.cfg
+++ /dev/null
@@ -1,65 +0,0 @@
-# Format: //devtools/kokoro/config/proto/build.proto
-
-# Build logs will be here
-action {
-  define_artifacts {
-    regex: "**/*sponge_log.xml"
-  }
-}
-
-# Download trampoline resources.
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
-
-# Use the trampoline script to run in docker.
-build_file: "python-api-core/.kokoro/trampoline_v2.sh"
-
-# Configure the docker image for kokoro-trampoline.
-env_vars: {
-    key: "TRAMPOLINE_IMAGE"
-    value: "gcr.io/cloud-devrel-kokoro-resources/python-lib-docs"
-}
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/python-api-core/.kokoro/publish-docs.sh"
-}
-
-env_vars: {
-    key: "STAGING_BUCKET"
-    value: "docs-staging"
-}
-
-env_vars: {
-    key: "V2_STAGING_BUCKET"
-    value: "docs-staging-v2"
-}
-
-# It will upload the docker image after successful builds.
-env_vars: {
-    key: "TRAMPOLINE_IMAGE_UPLOAD"
-    value: "true"
-}
-
-# It will always build the docker image.
-env_vars: {
-    key: "TRAMPOLINE_DOCKERFILE"
-    value: ".kokoro/docker/docs/Dockerfile"
-}
-
-# Fetch the token needed for reporting release status to GitHub
-before_action {
-  fetch_keystore {
-    keystore_resource {
-      keystore_config_id: 73713
-      keyname: "yoshi-automation-github-key"
-    }
-  }
-}
-
-before_action {
-  fetch_keystore {
-    keystore_resource {
-      keystore_config_id: 73713
-      keyname: "docuploader_service_account"
-    }
-  }
-}
\ No newline at end of file
diff --git a/.kokoro/docs/docs-presubmit.cfg b/.kokoro/docs/docs-presubmit.cfg
deleted file mode 100644
index d1ed51eb..00000000
--- a/.kokoro/docs/docs-presubmit.cfg
+++ /dev/null
@@ -1,28 +0,0 @@
-# Format: //devtools/kokoro/config/proto/build.proto
-
-env_vars: {
-    key: "STAGING_BUCKET"
-    value: "gcloud-python-test"
-}
-
-env_vars: {
-    key: "V2_STAGING_BUCKET"
-    value: "gcloud-python-test"
-}
-
-# We only upload the image in the main `docs` build.
-env_vars: {
-    key: "TRAMPOLINE_IMAGE_UPLOAD"
-    value: "false"
-}
-
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/python-api-core/.kokoro/build.sh"
-}
-
-# Only run this nox session.
-env_vars: {
-    key: "NOX_SESSION"
-    value: "docs docfx"
-}
diff --git a/.kokoro/docs/docs.cfg b/.kokoro/docs/docs.cfg
deleted file mode 100644
index 8f43917d..00000000
--- a/.kokoro/docs/docs.cfg
+++ /dev/null
@@ -1 +0,0 @@
-# Format: //devtools/kokoro/config/proto/build.proto
\ No newline at end of file
diff --git a/.kokoro/populate-secrets.sh b/.kokoro/populate-secrets.sh
index f5251425..c435402f 100755
--- a/.kokoro/populate-secrets.sh
+++ b/.kokoro/populate-secrets.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2020 Google LLC.
+# Copyright 2024 Google LLC.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/.kokoro/presubmit/prerelease-deps.cfg b/.kokoro/presubmit/prerelease-deps.cfg
new file mode 100644
index 00000000..3595fb43
--- /dev/null
+++ b/.kokoro/presubmit/prerelease-deps.cfg
@@ -0,0 +1,7 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Only run this nox session.
+env_vars: {
+    key: "NOX_SESSION"
+    value: "prerelease_deps"
+}
diff --git a/.kokoro/publish-docs.sh b/.kokoro/publish-docs.sh
deleted file mode 100755
index 8acb14e8..00000000
--- a/.kokoro/publish-docs.sh
+++ /dev/null
@@ -1,64 +0,0 @@
-#!/bin/bash
-# Copyright 2020 Google LLC
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-set -eo pipefail
-
-# Disable buffering, so that the logs stream through.
-export PYTHONUNBUFFERED=1
-
-export PATH="${HOME}/.local/bin:${PATH}"
-
-# Install nox
-python3 -m pip install --user --upgrade --quiet nox
-python3 -m nox --version
-
-# build docs
-nox -s docs
-
-python3 -m pip install --user gcp-docuploader
-
-# create metadata
-python3 -m docuploader create-metadata \
-  --name=$(jq --raw-output '.name // empty' .repo-metadata.json) \
-  --version=$(python3 setup.py --version) \
-  --language=$(jq --raw-output '.language // empty' .repo-metadata.json) \
-  --distribution-name=$(python3 setup.py --name) \
-  --product-page=$(jq --raw-output '.product_documentation // empty' .repo-metadata.json) \
-  --github-repository=$(jq --raw-output '.repo // empty' .repo-metadata.json) \
-  --issue-tracker=$(jq --raw-output '.issue_tracker // empty' .repo-metadata.json)
-
-cat docs.metadata
-
-# upload docs
-python3 -m docuploader upload docs/_build/html --metadata-file docs.metadata --staging-bucket "${STAGING_BUCKET}"
-
-
-# docfx yaml files
-nox -s docfx
-
-# create metadata.
-python3 -m docuploader create-metadata \
-  --name=$(jq --raw-output '.name // empty' .repo-metadata.json) \
-  --version=$(python3 setup.py --version) \
-  --language=$(jq --raw-output '.language // empty' .repo-metadata.json) \
-  --distribution-name=$(python3 setup.py --name) \
-  --product-page=$(jq --raw-output '.product_documentation // empty' .repo-metadata.json) \
-  --github-repository=$(jq --raw-output '.repo // empty' .repo-metadata.json) \
-  --issue-tracker=$(jq --raw-output '.issue_tracker // empty' .repo-metadata.json)
-
-cat docs.metadata
-
-# upload docs
-python3 -m docuploader upload docs/_build/html/docfx_yaml --metadata-file docs.metadata --destination-prefix docfx --staging-bucket "${V2_STAGING_BUCKET}"
diff --git a/.kokoro/release.sh b/.kokoro/release.sh
deleted file mode 100755
index 0728ce11..00000000
--- a/.kokoro/release.sh
+++ /dev/null
@@ -1,32 +0,0 @@
-#!/bin/bash
-# Copyright 2020 Google LLC
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     https://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-set -eo pipefail
-
-# Start the releasetool reporter
-python3 -m pip install gcp-releasetool
-python3 -m releasetool publish-reporter-script > /tmp/publisher-script; source /tmp/publisher-script
-
-# Ensure that we have the latest versions of Twine, Wheel, and Setuptools.
-python3 -m pip install --upgrade twine wheel setuptools
-
-# Disable buffering, so that the logs stream through.
-export PYTHONUNBUFFERED=1
-
-# Move into the package, build the distribution and upload.
-TWINE_PASSWORD=$(cat "${KOKORO_GFILE_DIR}/secret_manager/google-cloud-pypi-token")
-cd github/python-api-core
-python3 setup.py sdist bdist_wheel
-twine upload --username __token__ --password "${TWINE_PASSWORD}" dist/*
diff --git a/.kokoro/release/common.cfg b/.kokoro/release/common.cfg
deleted file mode 100644
index 586e7649..00000000
--- a/.kokoro/release/common.cfg
+++ /dev/null
@@ -1,30 +0,0 @@
-# Format: //devtools/kokoro/config/proto/build.proto
-
-# Build logs will be here
-action {
-  define_artifacts {
-    regex: "**/*sponge_log.xml"
-  }
-}
-
-# Download trampoline resources.
-gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
-
-# Use the trampoline script to run in docker.
-build_file: "python-api-core/.kokoro/trampoline.sh"
-
-# Configure the docker image for kokoro-trampoline.
-env_vars: {
-    key: "TRAMPOLINE_IMAGE"
-    value: "gcr.io/cloud-devrel-kokoro-resources/python-multi"
-}
-env_vars: {
-    key: "TRAMPOLINE_BUILD_FILE"
-    value: "github/python-api-core/.kokoro/release.sh"
-}
-
-# Tokens needed to report release status back to GitHub
-env_vars: {
-  key: "SECRET_MANAGER_KEYS"
-  value: "releasetool-publish-reporter-app,releasetool-publish-reporter-googleapis-installation,releasetool-publish-reporter-pem,google-cloud-pypi-token"
-}
diff --git a/.kokoro/release/release.cfg b/.kokoro/release/release.cfg
deleted file mode 100644
index 8f43917d..00000000
--- a/.kokoro/release/release.cfg
+++ /dev/null
@@ -1 +0,0 @@
-# Format: //devtools/kokoro/config/proto/build.proto
\ No newline at end of file
diff --git a/.kokoro/samples/lint/common.cfg b/.kokoro/samples/lint/common.cfg
index f5dddb4b..1a2b87b2 100644
--- a/.kokoro/samples/lint/common.cfg
+++ b/.kokoro/samples/lint/common.cfg
@@ -31,4 +31,4 @@ gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/python-docs-samples"
 gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
 
 # Use the trampoline script to run in docker.
-build_file: "python-api-core/.kokoro/trampoline.sh"
\ No newline at end of file
+build_file: "python-api-core/.kokoro/trampoline_v2.sh"
\ No newline at end of file
diff --git a/.kokoro/samples/python3.6/common.cfg b/.kokoro/samples/python3.10/common.cfg
similarity index 87%
rename from .kokoro/samples/python3.6/common.cfg
rename to .kokoro/samples/python3.10/common.cfg
index 7b4f5cd0..40fb8d81 100644
--- a/.kokoro/samples/python3.6/common.cfg
+++ b/.kokoro/samples/python3.10/common.cfg
@@ -10,13 +10,13 @@ action {
 # Specify which tests to run
 env_vars: {
     key: "RUN_TESTS_SESSION"
-    value: "py-3.6"
+    value: "py-3.10"
 }
 
 # Declare build specific Cloud project.
 env_vars: {
     key: "BUILD_SPECIFIC_GCLOUD_PROJECT"
-    value: "python-docs-samples-tests-py36"
+    value: "python-docs-samples-tests-310"
 }
 
 env_vars: {
@@ -37,4 +37,4 @@ gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/python-docs-samples"
 gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
 
 # Use the trampoline script to run in docker.
-build_file: "python-api-core/.kokoro/trampoline.sh"
\ No newline at end of file
+build_file: "python-api-core/.kokoro/trampoline_v2.sh"
\ No newline at end of file
diff --git a/.kokoro/samples/python3.6/presubmit.cfg b/.kokoro/samples/python3.10/continuous.cfg
similarity index 100%
rename from .kokoro/samples/python3.6/presubmit.cfg
rename to .kokoro/samples/python3.10/continuous.cfg
diff --git a/.kokoro/samples/python3.6/periodic-head.cfg b/.kokoro/samples/python3.10/periodic-head.cfg
similarity index 100%
rename from .kokoro/samples/python3.6/periodic-head.cfg
rename to .kokoro/samples/python3.10/periodic-head.cfg
diff --git a/.kokoro/samples/python3.6/periodic.cfg b/.kokoro/samples/python3.10/periodic.cfg
similarity index 98%
rename from .kokoro/samples/python3.6/periodic.cfg
rename to .kokoro/samples/python3.10/periodic.cfg
index 50fec964..71cd1e59 100644
--- a/.kokoro/samples/python3.6/periodic.cfg
+++ b/.kokoro/samples/python3.10/periodic.cfg
@@ -3,4 +3,4 @@
 env_vars: {
     key: "INSTALL_LIBRARY_FROM_SOURCE"
     value: "False"
-}
\ No newline at end of file
+}
diff --git a/.kokoro/samples/python3.10/presubmit.cfg b/.kokoro/samples/python3.10/presubmit.cfg
new file mode 100644
index 00000000..a1c8d975
--- /dev/null
+++ b/.kokoro/samples/python3.10/presubmit.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
\ No newline at end of file
diff --git a/.kokoro/samples/python3.11/common.cfg b/.kokoro/samples/python3.11/common.cfg
new file mode 100644
index 00000000..d3597f08
--- /dev/null
+++ b/.kokoro/samples/python3.11/common.cfg
@@ -0,0 +1,40 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Build logs will be here
+action {
+  define_artifacts {
+    regex: "**/*sponge_log.xml"
+  }
+}
+
+# Specify which tests to run
+env_vars: {
+    key: "RUN_TESTS_SESSION"
+    value: "py-3.11"
+}
+
+# Declare build specific Cloud project.
+env_vars: {
+    key: "BUILD_SPECIFIC_GCLOUD_PROJECT"
+    value: "python-docs-samples-tests-311"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-api-core/.kokoro/test-samples.sh"
+}
+
+# Configure the docker image for kokoro-trampoline.
+env_vars: {
+    key: "TRAMPOLINE_IMAGE"
+    value: "gcr.io/cloud-devrel-kokoro-resources/python-samples-testing-docker"
+}
+
+# Download secrets for samples
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/python-docs-samples"
+
+# Download trampoline resources.
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
+
+# Use the trampoline script to run in docker.
+build_file: "python-api-core/.kokoro/trampoline_v2.sh"
\ No newline at end of file
diff --git a/.kokoro/samples/python3.6/continuous.cfg b/.kokoro/samples/python3.11/continuous.cfg
similarity index 97%
rename from .kokoro/samples/python3.6/continuous.cfg
rename to .kokoro/samples/python3.11/continuous.cfg
index 7218af14..a1c8d975 100644
--- a/.kokoro/samples/python3.6/continuous.cfg
+++ b/.kokoro/samples/python3.11/continuous.cfg
@@ -3,5 +3,4 @@
 env_vars: {
     key: "INSTALL_LIBRARY_FROM_SOURCE"
     value: "True"
-}
-
+}
\ No newline at end of file
diff --git a/.kokoro/samples/python3.11/periodic-head.cfg b/.kokoro/samples/python3.11/periodic-head.cfg
new file mode 100644
index 00000000..a18c0cfc
--- /dev/null
+++ b/.kokoro/samples/python3.11/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-api-core/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/samples/python3.11/periodic.cfg b/.kokoro/samples/python3.11/periodic.cfg
new file mode 100644
index 00000000..71cd1e59
--- /dev/null
+++ b/.kokoro/samples/python3.11/periodic.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "False"
+}
diff --git a/.kokoro/samples/python3.11/presubmit.cfg b/.kokoro/samples/python3.11/presubmit.cfg
new file mode 100644
index 00000000..a1c8d975
--- /dev/null
+++ b/.kokoro/samples/python3.11/presubmit.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
\ No newline at end of file
diff --git a/.kokoro/samples/python3.12/common.cfg b/.kokoro/samples/python3.12/common.cfg
new file mode 100644
index 00000000..8a5840a7
--- /dev/null
+++ b/.kokoro/samples/python3.12/common.cfg
@@ -0,0 +1,40 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Build logs will be here
+action {
+  define_artifacts {
+    regex: "**/*sponge_log.xml"
+  }
+}
+
+# Specify which tests to run
+env_vars: {
+    key: "RUN_TESTS_SESSION"
+    value: "py-3.12"
+}
+
+# Declare build specific Cloud project.
+env_vars: {
+    key: "BUILD_SPECIFIC_GCLOUD_PROJECT"
+    value: "python-docs-samples-tests-312"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-api-core/.kokoro/test-samples.sh"
+}
+
+# Configure the docker image for kokoro-trampoline.
+env_vars: {
+    key: "TRAMPOLINE_IMAGE"
+    value: "gcr.io/cloud-devrel-kokoro-resources/python-samples-testing-docker"
+}
+
+# Download secrets for samples
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/python-docs-samples"
+
+# Download trampoline resources.
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
+
+# Use the trampoline script to run in docker.
+build_file: "python-api-core/.kokoro/trampoline_v2.sh"
\ No newline at end of file
diff --git a/.kokoro/samples/python3.12/continuous.cfg b/.kokoro/samples/python3.12/continuous.cfg
new file mode 100644
index 00000000..a1c8d975
--- /dev/null
+++ b/.kokoro/samples/python3.12/continuous.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
\ No newline at end of file
diff --git a/.kokoro/samples/python3.12/periodic-head.cfg b/.kokoro/samples/python3.12/periodic-head.cfg
new file mode 100644
index 00000000..a18c0cfc
--- /dev/null
+++ b/.kokoro/samples/python3.12/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-api-core/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/samples/python3.12/periodic.cfg b/.kokoro/samples/python3.12/periodic.cfg
new file mode 100644
index 00000000..71cd1e59
--- /dev/null
+++ b/.kokoro/samples/python3.12/periodic.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "False"
+}
diff --git a/.kokoro/samples/python3.12/presubmit.cfg b/.kokoro/samples/python3.12/presubmit.cfg
new file mode 100644
index 00000000..a1c8d975
--- /dev/null
+++ b/.kokoro/samples/python3.12/presubmit.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
\ No newline at end of file
diff --git a/.kokoro/samples/python3.13/common.cfg b/.kokoro/samples/python3.13/common.cfg
new file mode 100644
index 00000000..2a4199f4
--- /dev/null
+++ b/.kokoro/samples/python3.13/common.cfg
@@ -0,0 +1,40 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+# Build logs will be here
+action {
+  define_artifacts {
+    regex: "**/*sponge_log.xml"
+  }
+}
+
+# Specify which tests to run
+env_vars: {
+    key: "RUN_TESTS_SESSION"
+    value: "py-3.13"
+}
+
+# Declare build specific Cloud project.
+env_vars: {
+    key: "BUILD_SPECIFIC_GCLOUD_PROJECT"
+    value: "python-docs-samples-tests-313"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-api-core/.kokoro/test-samples.sh"
+}
+
+# Configure the docker image for kokoro-trampoline.
+env_vars: {
+    key: "TRAMPOLINE_IMAGE"
+    value: "gcr.io/cloud-devrel-kokoro-resources/python-samples-testing-docker"
+}
+
+# Download secrets for samples
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/python-docs-samples"
+
+# Download trampoline resources.
+gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
+
+# Use the trampoline script to run in docker.
+build_file: "python-api-core/.kokoro/trampoline_v2.sh"
diff --git a/.kokoro/samples/python3.13/continuous.cfg b/.kokoro/samples/python3.13/continuous.cfg
new file mode 100644
index 00000000..a1c8d975
--- /dev/null
+++ b/.kokoro/samples/python3.13/continuous.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
\ No newline at end of file
diff --git a/.kokoro/samples/python3.13/periodic-head.cfg b/.kokoro/samples/python3.13/periodic-head.cfg
new file mode 100644
index 00000000..a18c0cfc
--- /dev/null
+++ b/.kokoro/samples/python3.13/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-api-core/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/samples/python3.13/periodic.cfg b/.kokoro/samples/python3.13/periodic.cfg
new file mode 100644
index 00000000..71cd1e59
--- /dev/null
+++ b/.kokoro/samples/python3.13/periodic.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "False"
+}
diff --git a/.kokoro/samples/python3.13/presubmit.cfg b/.kokoro/samples/python3.13/presubmit.cfg
new file mode 100644
index 00000000..a1c8d975
--- /dev/null
+++ b/.kokoro/samples/python3.13/presubmit.cfg
@@ -0,0 +1,6 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
\ No newline at end of file
diff --git a/.kokoro/samples/python3.7/common.cfg b/.kokoro/samples/python3.7/common.cfg
index 1198d7ba..a3aa10b5 100644
--- a/.kokoro/samples/python3.7/common.cfg
+++ b/.kokoro/samples/python3.7/common.cfg
@@ -37,4 +37,4 @@ gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/python-docs-samples"
 gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
 
 # Use the trampoline script to run in docker.
-build_file: "python-api-core/.kokoro/trampoline.sh"
\ No newline at end of file
+build_file: "python-api-core/.kokoro/trampoline_v2.sh"
\ No newline at end of file
diff --git a/.kokoro/samples/python3.7/periodic.cfg b/.kokoro/samples/python3.7/periodic.cfg
index 50fec964..71cd1e59 100644
--- a/.kokoro/samples/python3.7/periodic.cfg
+++ b/.kokoro/samples/python3.7/periodic.cfg
@@ -3,4 +3,4 @@
 env_vars: {
     key: "INSTALL_LIBRARY_FROM_SOURCE"
     value: "False"
-}
\ No newline at end of file
+}
diff --git a/.kokoro/samples/python3.8/common.cfg b/.kokoro/samples/python3.8/common.cfg
index b7ec7f5e..20c941aa 100644
--- a/.kokoro/samples/python3.8/common.cfg
+++ b/.kokoro/samples/python3.8/common.cfg
@@ -37,4 +37,4 @@ gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/python-docs-samples"
 gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
 
 # Use the trampoline script to run in docker.
-build_file: "python-api-core/.kokoro/trampoline.sh"
\ No newline at end of file
+build_file: "python-api-core/.kokoro/trampoline_v2.sh"
\ No newline at end of file
diff --git a/.kokoro/samples/python3.8/periodic.cfg b/.kokoro/samples/python3.8/periodic.cfg
index 50fec964..71cd1e59 100644
--- a/.kokoro/samples/python3.8/periodic.cfg
+++ b/.kokoro/samples/python3.8/periodic.cfg
@@ -3,4 +3,4 @@
 env_vars: {
     key: "INSTALL_LIBRARY_FROM_SOURCE"
     value: "False"
-}
\ No newline at end of file
+}
diff --git a/.kokoro/samples/python3.9/common.cfg b/.kokoro/samples/python3.9/common.cfg
index cf034ec1..234887c6 100644
--- a/.kokoro/samples/python3.9/common.cfg
+++ b/.kokoro/samples/python3.9/common.cfg
@@ -37,4 +37,4 @@ gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/python-docs-samples"
 gfile_resources: "/bigstore/cloud-devrel-kokoro-resources/trampoline"
 
 # Use the trampoline script to run in docker.
-build_file: "python-api-core/.kokoro/trampoline.sh"
\ No newline at end of file
+build_file: "python-api-core/.kokoro/trampoline_v2.sh"
\ No newline at end of file
diff --git a/.kokoro/samples/python3.9/periodic.cfg b/.kokoro/samples/python3.9/periodic.cfg
index 50fec964..71cd1e59 100644
--- a/.kokoro/samples/python3.9/periodic.cfg
+++ b/.kokoro/samples/python3.9/periodic.cfg
@@ -3,4 +3,4 @@
 env_vars: {
     key: "INSTALL_LIBRARY_FROM_SOURCE"
     value: "False"
-}
\ No newline at end of file
+}
diff --git a/.kokoro/test-samples-against-head.sh b/.kokoro/test-samples-against-head.sh
index a7858e4c..e9d8bd79 100755
--- a/.kokoro/test-samples-against-head.sh
+++ b/.kokoro/test-samples-against-head.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2020 Google LLC
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -23,6 +23,4 @@ set -eo pipefail
 # Enables `**` to include files nested inside sub-folders
 shopt -s globstar
 
-cd github/python-api-core
-
 exec .kokoro/test-samples-impl.sh
diff --git a/.kokoro/test-samples-impl.sh b/.kokoro/test-samples-impl.sh
index 311a8d54..53e365bc 100755
--- a/.kokoro/test-samples-impl.sh
+++ b/.kokoro/test-samples-impl.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2021 Google LLC
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -33,7 +33,8 @@ export PYTHONUNBUFFERED=1
 env | grep KOKORO
 
 # Install nox
-python3.6 -m pip install --upgrade --quiet nox
+# `virtualenv==20.26.6` is added for Python 3.7 compatibility
+python3.9 -m pip install --upgrade --quiet nox virtualenv==20.26.6
 
 # Use secrets acessor service account to get secrets
 if [[ -f "${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" ]]; then
@@ -76,11 +77,11 @@ for file in samples/**/requirements.txt; do
     echo "------------------------------------------------------------"
 
     # Use nox to execute the tests for the project.
-    python3.6 -m nox -s "$RUN_TESTS_SESSION"
+    python3.9 -m nox -s "$RUN_TESTS_SESSION"
     EXIT=$?
 
     # If this is a periodic build, send the test log to the FlakyBot.
-    # See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
+    # See https://github.com/googleapis/repo-automation-bots/tree/main/packages/flakybot.
     if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
       chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
       $KOKORO_GFILE_DIR/linux_amd64/flakybot
diff --git a/.kokoro/test-samples.sh b/.kokoro/test-samples.sh
index ee3146bd..7933d820 100755
--- a/.kokoro/test-samples.sh
+++ b/.kokoro/test-samples.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2020 Google LLC
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -24,8 +24,6 @@ set -eo pipefail
 # Enables `**` to include files nested inside sub-folders
 shopt -s globstar
 
-cd github/python-api-core
-
 # Run periodic samples tests at latest release
 if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
     # preserving the test runner implementation.
diff --git a/.kokoro/trampoline.sh b/.kokoro/trampoline.sh
index f39236e9..48f79699 100755
--- a/.kokoro/trampoline.sh
+++ b/.kokoro/trampoline.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Copyright 2017 Google Inc.
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/.kokoro/trampoline_v2.sh b/.kokoro/trampoline_v2.sh
index 4af6cdc2..35fa5292 100755
--- a/.kokoro/trampoline_v2.sh
+++ b/.kokoro/trampoline_v2.sh
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# Copyright 2020 Google LLC
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 62eb5a77..1d74695f 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,4 +1,4 @@
-# Copyright 2021 Google LLC
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -22,10 +22,10 @@ repos:
     -   id: end-of-file-fixer
     -   id: check-yaml
 -   repo: https://github.com/psf/black
-    rev: 19.10b0
+    rev: 23.7.0
     hooks:
     - id: black
--   repo: https://gitlab.com/pycqa/flake8
-    rev: 3.9.2
+-   repo: https://github.com/pycqa/flake8
+    rev: 6.1.0
     hooks:
     - id: flake8
diff --git a/.repo-metadata.json b/.repo-metadata.json
index 59aa936d..0f0abd93 100644
--- a/.repo-metadata.json
+++ b/.repo-metadata.json
@@ -1,10 +1,12 @@
 {
-  "name": "google-api-core",
-  "name_pretty": "Google API client core library",
-  "client_documentation": "https://googleapis.dev/python/google-api-core/latest",
-  "release_level": "ga",
-  "language": "python",
-  "library_type": "CORE",
-  "repo": "googleapis/python-api-core",
-  "distribution_name": "google-api-core"
-}
\ No newline at end of file
+    "name": "google-api-core",
+    "name_pretty": "Google API client core library",
+    "client_documentation": "https://googleapis.dev/python/google-api-core/latest",
+    "release_level": "stable",
+    "language": "python",
+    "library_type": "CORE",
+    "repo": "googleapis/python-api-core",
+    "distribution_name": "google-api-core",
+    "default_version": "",
+    "codeowner_team": "@googleapis/actools-python"
+}
diff --git a/.trampolinerc b/.trampolinerc
index 383b6ec8..00801523 100644
--- a/.trampolinerc
+++ b/.trampolinerc
@@ -1,4 +1,4 @@
-# Copyright 2020 Google LLC
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -12,19 +12,28 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# Template for .trampolinerc
-
 # Add required env vars here.
 required_envvars+=(
-    "STAGING_BUCKET"
-    "V2_STAGING_BUCKET"
 )
 
 # Add env vars which are passed down into the container here.
 pass_down_envvars+=(
+    "NOX_SESSION"
+    ###############
+    # Docs builds
+    ###############
     "STAGING_BUCKET"
     "V2_STAGING_BUCKET"
-    "NOX_SESSION"
+    ##################
+    # Samples builds
+    ##################
+    "INSTALL_LIBRARY_FROM_SOURCE"
+    "RUN_TESTS_SESSION"
+    "BUILD_SPECIFIC_GCLOUD_PROJECT"
+    # Target directories.
+    "RUN_TESTS_DIRS"
+    # The nox session to run.
+    "RUN_TESTS_SESSION"
 )
 
 # Prevent unintentional override on the default image.
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e8e5e7a5..e118fe46 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,443 @@
 
 [1]: https://pypi.org/project/google-api-core/#history
 
+## [2.24.2](https://github.com/googleapis/python-api-core/compare/v2.24.1...v2.24.2) (2025-03-06)
+
+
+### Bug Fixes
+
+* **deps:** Allow protobuf 6.x ([#804](https://github.com/googleapis/python-api-core/issues/804)) ([687be7c](https://github.com/googleapis/python-api-core/commit/687be7cbf629a61feb43ef37d3d920fa32b2d636))
+
+## [2.24.1](https://github.com/googleapis/python-api-core/compare/v2.24.0...v2.24.1) (2025-01-24)
+
+
+### Bug Fixes
+
+* Memory leak in bidi classes ([#770](https://github.com/googleapis/python-api-core/issues/770)) ([c1b8afa](https://github.com/googleapis/python-api-core/commit/c1b8afa4e2abe256e70651defccdc285f104ed19))
+* Resolve the issue where rpc timeout of 0 is used when timeout expires ([#776](https://github.com/googleapis/python-api-core/issues/776)) ([a5604a5](https://github.com/googleapis/python-api-core/commit/a5604a55070c6d92618d078191bf99f4c168d5f6))
+
+
+### Documentation
+
+* Add warnings regarding consuming externally sourced credentials ([#783](https://github.com/googleapis/python-api-core/issues/783)) ([0ec1825](https://github.com/googleapis/python-api-core/commit/0ec18254b90721684679a98bcacef4615467a227))
+
+## [2.24.0](https://github.com/googleapis/python-api-core/compare/v2.23.0...v2.24.0) (2024-12-06)
+
+
+### Features
+
+* Add automatic logging config to support debug logging ([#754](https://github.com/googleapis/python-api-core/issues/754)) ([d18d9b5](https://github.com/googleapis/python-api-core/commit/d18d9b5131162b44eebcc0859a7aca1198a2ac06))
+* Update recognized logging fields ([#766](https://github.com/googleapis/python-api-core/issues/766)) ([5f80f77](https://github.com/googleapis/python-api-core/commit/5f80f778bc25d878b3187c6138077ad8c6bcd35f))
+
+## [2.23.0](https://github.com/googleapis/python-api-core/compare/v2.22.0...v2.23.0) (2024-11-11)
+
+
+### Features
+
+* Migrate to pyproject.toml ([#736](https://github.com/googleapis/python-api-core/issues/736)) ([159e9a4](https://github.com/googleapis/python-api-core/commit/159e9a49525937f18a55c38136aae32575424d55))
+
+## [2.22.0](https://github.com/googleapis/python-api-core/compare/v2.21.0...v2.22.0) (2024-10-25)
+
+
+### Features
+
+* Add support for python 3.13 ([#696](https://github.com/googleapis/python-api-core/issues/696)) ([46b3d3a](https://github.com/googleapis/python-api-core/commit/46b3d3abaa1bae28e9d788d7c3006224cd6f74d5))
+
+
+### Bug Fixes
+
+* Add type hints to ClientOptions ([#735](https://github.com/googleapis/python-api-core/issues/735)) ([b91ed19](https://github.com/googleapis/python-api-core/commit/b91ed19210148dfa49ec790c4dd5f4a7bff80954))
+* Improve `Any` decode error ([#712](https://github.com/googleapis/python-api-core/issues/712)) ([0d5ed37](https://github.com/googleapis/python-api-core/commit/0d5ed37c96f9b40bccae98e228163a88abeb1763))
+* Require proto-plus >= 1.25.0 for Python 3.13 ([#740](https://github.com/googleapis/python-api-core/issues/740)) ([a26313e](https://github.com/googleapis/python-api-core/commit/a26313e1cb12e44aa498f12622edccc0c83ba0c3))
+* Switch to unittest.mock from mock ([#713](https://github.com/googleapis/python-api-core/issues/713)) ([8c53381](https://github.com/googleapis/python-api-core/commit/8c533819b7e212aa2f1d695a7ce08629f4fb2daf))
+
+## [2.21.0](https://github.com/googleapis/python-api-core/compare/v2.20.0...v2.21.0) (2024-10-07)
+
+
+### Features
+
+* Add support for asynchronous long running operations ([#724](https://github.com/googleapis/python-api-core/issues/724)) ([aaed69b](https://github.com/googleapis/python-api-core/commit/aaed69b6f1d694cd7e561e2aa03fdd8d6cfb369a))
+
+
+### Bug Fixes
+
+* Set chunk size for async stream content ([#702](https://github.com/googleapis/python-api-core/issues/702)) ([45b8a6d](https://github.com/googleapis/python-api-core/commit/45b8a6db5a5c75acdd8be896d0152f11608c7e51))
+
+## [2.20.0](https://github.com/googleapis/python-api-core/compare/v2.19.2...v2.20.0) (2024-09-18)
+
+
+### Features
+
+* Add async unsupported paramater exception ([#694](https://github.com/googleapis/python-api-core/issues/694)) ([8c137fe](https://github.com/googleapis/python-api-core/commit/8c137feb6e880fdd93d1248d9b6c10002dc3c096))
+* Add support for asynchronous rest streaming ([#686](https://github.com/googleapis/python-api-core/issues/686)) ([1b7bb6d](https://github.com/googleapis/python-api-core/commit/1b7bb6d1b721e4ee1561e8e4a347846d7fdd7c27))
+* Add support for creating exceptions from an asynchronous response ([#688](https://github.com/googleapis/python-api-core/issues/688)) ([1c4b0d0](https://github.com/googleapis/python-api-core/commit/1c4b0d079f2103a7b5562371a7bd1ada92528de3))
+
+## [2.19.2](https://github.com/googleapis/python-api-core/compare/v2.19.1...v2.19.2) (2024-08-16)
+
+
+### Bug Fixes
+
+* Fail gracefully if could not import `rpc_status` module ([#680](https://github.com/googleapis/python-api-core/issues/680)) ([7ccbf57](https://github.com/googleapis/python-api-core/commit/7ccbf5738fa236649f9a155055c71789362b5c4c))
+
+## [2.19.1](https://github.com/googleapis/python-api-core/compare/v2.19.0...v2.19.1) (2024-06-19)
+
+
+### Bug Fixes
+
+* Add support for protobuf 5.x ([#644](https://github.com/googleapis/python-api-core/issues/644)) ([fda0ca6](https://github.com/googleapis/python-api-core/commit/fda0ca6f0664ac5044671591ed62618175a7393f))
+* Ignore unknown fields in rest streaming. ([#651](https://github.com/googleapis/python-api-core/issues/651)) ([1203fb9](https://github.com/googleapis/python-api-core/commit/1203fb97d2685535f89113e944c4764c1deb595e))
+
+## [2.19.0](https://github.com/googleapis/python-api-core/compare/v2.18.0...v2.19.0) (2024-04-29)
+
+
+### Features
+
+* Add google.api_core.version_header ([#638](https://github.com/googleapis/python-api-core/issues/638)) ([a7b53e9](https://github.com/googleapis/python-api-core/commit/a7b53e9e9a7deb88baf92a2827958429e3677069))
+
+## [2.18.0](https://github.com/googleapis/python-api-core/compare/v2.17.1...v2.18.0) (2024-03-20)
+
+
+### Features
+
+* Add common logic for supporting universe domain ([#621](https://github.com/googleapis/python-api-core/issues/621)) ([94f2ca3](https://github.com/googleapis/python-api-core/commit/94f2ca3b4d094e6e10154634d3463d07ebea2035))
+
+
+### Bug Fixes
+
+* Add _registered_method to grpc ChannelStub ([#614](https://github.com/googleapis/python-api-core/issues/614)) ([5eaaea8](https://github.com/googleapis/python-api-core/commit/5eaaea8a989f8bdbdb5fbc95a155a20837c87f42))
+* **deps:** Require proto-plus >= 1.22.3 ([#626](https://github.com/googleapis/python-api-core/issues/626)) ([4fed37c](https://github.com/googleapis/python-api-core/commit/4fed37cbc32122f156e38250b5fa8b2b08a787a1))
+
+## [2.17.1](https://github.com/googleapis/python-api-core/compare/v2.17.0...v2.17.1) (2024-02-13)
+
+
+### Bug Fixes
+
+* Resolve issue handling protobuf responses in rest streaming ([#604](https://github.com/googleapis/python-api-core/issues/604)) ([bcebc92](https://github.com/googleapis/python-api-core/commit/bcebc92eca69dae81c5e546d526c92b164a6b3b4))
+
+## [2.17.0](https://github.com/googleapis/python-api-core/compare/v2.16.2...v2.17.0) (2024-02-06)
+
+
+### Features
+
+* Add attempt_direct_path argument to create_channel ([#583](https://github.com/googleapis/python-api-core/issues/583)) ([94726e7](https://github.com/googleapis/python-api-core/commit/94726e739698035b00667983f854c600252abd28))
+
+
+### Bug Fixes
+
+* Retry constructors methods support None ([#592](https://github.com/googleapis/python-api-core/issues/592)) ([416203c](https://github.com/googleapis/python-api-core/commit/416203c1888934670bfeccafe5f5469f87314512))
+
+## [2.16.2](https://github.com/googleapis/python-api-core/compare/v2.16.1...v2.16.2) (2024-02-02)
+
+
+### Bug Fixes
+
+* Spelling error `a,out` -> `amount` ([#596](https://github.com/googleapis/python-api-core/issues/596)) ([88688b1](https://github.com/googleapis/python-api-core/commit/88688b1625c4dab0df6124a0560f550eb322500f))
+
+## [2.16.1](https://github.com/googleapis/python-api-core/compare/v2.16.0...v2.16.1) (2024-01-30)
+
+
+### Bug Fixes
+
+* Fix broken import for google.api_core.retry_async.AsyncRetry ([#587](https://github.com/googleapis/python-api-core/issues/587)) ([ac012c0](https://github.com/googleapis/python-api-core/commit/ac012c04c69b8bbe72962f0d0d9e9536c0b4a524))
+
+## [2.16.0](https://github.com/googleapis/python-api-core/compare/v2.15.0...v2.16.0) (2024-01-29)
+
+
+### Features
+
+* Retry and retry_async support streaming rpcs ([#495](https://github.com/googleapis/python-api-core/issues/495)) ([17ff5f1](https://github.com/googleapis/python-api-core/commit/17ff5f1d83a9a6f50a0226fb0e794634bd584f17))
+
+## [2.15.0](https://github.com/googleapis/python-api-core/compare/v2.14.0...v2.15.0) (2023-12-07)
+
+
+### Features
+
+* Add support for Python 3.12 ([#557](https://github.com/googleapis/python-api-core/issues/557)) ([091b4f1](https://github.com/googleapis/python-api-core/commit/091b4f1c7fcc59c3f2a02ee44fd3c30b78423f12))
+* Add type annotations to wrapped grpc calls ([#554](https://github.com/googleapis/python-api-core/issues/554)) ([fc12b40](https://github.com/googleapis/python-api-core/commit/fc12b40bfc6e0c4bb313196e2e3a9c9374ce1c45))
+* Add universe_domain argument to ClientOptions ([3069ef4](https://github.com/googleapis/python-api-core/commit/3069ef4b9123ddb64841cbb7bbb183b53d502e0a))
+* Introduce compatibility with native namespace packages ([#561](https://github.com/googleapis/python-api-core/issues/561)) ([bd82827](https://github.com/googleapis/python-api-core/commit/bd82827108f1eeb6c05cfacf6c044b2afacc18a2))
+
+
+### Bug Fixes
+
+* Fix regression in `bidi` causing `Thread-ConsumeBidirectionalStream caught unexpected exception  and will exit` ([#562](https://github.com/googleapis/python-api-core/issues/562)) ([40c8ae0](https://github.com/googleapis/python-api-core/commit/40c8ae0cf1f797e31e106461164e22db4fb2d3d9))
+* Replace deprecated `datetime.datetime.utcnow()` ([#552](https://github.com/googleapis/python-api-core/issues/552)) ([448923a](https://github.com/googleapis/python-api-core/commit/448923acf277a70e8704c949311bf4feaef8cab6)), closes [#540](https://github.com/googleapis/python-api-core/issues/540)
+
+## [2.14.0](https://github.com/googleapis/python-api-core/compare/v2.13.1...v2.14.0) (2023-11-09)
+
+
+### Features
+
+* Support with_call for wrapped rpcs ([#550](https://github.com/googleapis/python-api-core/issues/550)) ([01a57a7](https://github.com/googleapis/python-api-core/commit/01a57a745f4c8345c9c93412c27dd416b49f5953))
+
+## [2.13.1](https://github.com/googleapis/python-api-core/compare/v2.13.0...v2.13.1) (2023-11-09)
+
+
+### Bug Fixes
+
+* Update async client to use async retry ([#544](https://github.com/googleapis/python-api-core/issues/544)) ([f21bb32](https://github.com/googleapis/python-api-core/commit/f21bb32b8e6310116a642a6e6b6dd8e44e30e656))
+
+## [2.13.0](https://github.com/googleapis/python-api-core/compare/v2.12.0...v2.13.0) (2023-11-03)
+
+
+### Features
+
+* Add caching to routing header calculation ([#526](https://github.com/googleapis/python-api-core/issues/526)) ([6251eab](https://github.com/googleapis/python-api-core/commit/6251eab3fca5f7e509cb9b6e476ce1184094b711))
+
+
+### Bug Fixes
+
+* Add warning to retry target to avoid incorrect usage ([#543](https://github.com/googleapis/python-api-core/issues/543)) ([bfb40e6](https://github.com/googleapis/python-api-core/commit/bfb40e6929ef47be7a6464d2f1e0d06595736b8d))
+* Drop usage of distutils ([#541](https://github.com/googleapis/python-api-core/issues/541)) ([4bd9e10](https://github.com/googleapis/python-api-core/commit/4bd9e10f20eea227c88e3e1496010cca6dd8a270))
+* Ensure exception is available when BackgroundConsumer open stream fails ([#357](https://github.com/googleapis/python-api-core/issues/357)) ([405272c](https://github.com/googleapis/python-api-core/commit/405272c05f8c6d20e242c6172b01f78f0fd3bf32))
+
+## [2.12.0](https://github.com/googleapis/python-api-core/compare/v2.11.1...v2.12.0) (2023-09-07)
+
+
+### Features
+
+* Add a little bit of typing to google.api_core.retry ([#453](https://github.com/googleapis/python-api-core/issues/453)) ([2477ab9](https://github.com/googleapis/python-api-core/commit/2477ab9ea5c2e863a493fb7ebebaa429a44ea096))
+* Add grpc Compression argument to channels and methods ([#451](https://github.com/googleapis/python-api-core/issues/451)) ([bdebd63](https://github.com/googleapis/python-api-core/commit/bdebd6331f9c0d3d1a8ceaf274f07d2ed75bfe92))
+
+
+### Documentation
+
+* Fix a typo in google/api_core/page_iterator.py ([#511](https://github.com/googleapis/python-api-core/issues/511)) ([c0ce73c](https://github.com/googleapis/python-api-core/commit/c0ce73c4de53ad694fe36d17408998aa1230398f))
+
+## [2.11.1](https://github.com/googleapis/python-api-core/compare/v2.11.0...v2.11.1) (2023-06-12)
+
+
+### Bug Fixes
+
+* Add actionable errors for GCE long running operations ([#498](https://github.com/googleapis/python-api-core/issues/498)) ([7dfc3a7](https://github.com/googleapis/python-api-core/commit/7dfc3a7a439243f05238a11b68a31720fde1769e))
+* Invalid `dev` version identifiers in `setup.py` ([#505](https://github.com/googleapis/python-api-core/issues/505)) ([8844edb](https://github.com/googleapis/python-api-core/commit/8844edb1e802040810918a12bc9ff89104da38d4))
+
+## [2.11.0](https://github.com/googleapis/python-api-core/compare/v2.10.2...v2.11.0) (2022-11-10)
+
+
+### Features
+
+* Add support for Python 3.11 ([#466](https://github.com/googleapis/python-api-core/issues/466)) ([ff379e3](https://github.com/googleapis/python-api-core/commit/ff379e304c353bcab734e1c4706b74b356a1e932))
+* Allow representing enums with their unqualified symbolic names in headers ([#465](https://github.com/googleapis/python-api-core/issues/465)) ([522b98e](https://github.com/googleapis/python-api-core/commit/522b98ecc1ebd1c2280d3d7c73a02f6e4fb528d4))
+
+
+### Bug Fixes
+
+* Major refactoring of Polling, Retry and Timeout logic ([#462](https://github.com/googleapis/python-api-core/issues/462)) ([434253d](https://github.com/googleapis/python-api-core/commit/434253de16d9efdf984ddb64c409706cda1d5f82))
+* Require google-auth >= 2.14.1 ([#463](https://github.com/googleapis/python-api-core/issues/463)) ([7cc329f](https://github.com/googleapis/python-api-core/commit/7cc329fe1498b0a4285123448e4ea80c6a780d47))
+
+## [2.10.2](https://github.com/googleapis/python-api-core/compare/v2.10.1...v2.10.2) (2022-10-08)
+
+
+### Bug Fixes
+
+* **deps:** Allow protobuf 3.19.5 ([#459](https://github.com/googleapis/python-api-core/issues/459)) ([e949364](https://github.com/googleapis/python-api-core/commit/e949364ce3a2c4c3cdb2658054d4793aa942d999))
+
+## [2.10.1](https://github.com/googleapis/python-api-core/compare/v2.10.0...v2.10.1) (2022-09-14)
+
+
+### Bug Fixes
+
+* Improve transcoding error message ([#442](https://github.com/googleapis/python-api-core/issues/442)) ([538df80](https://github.com/googleapis/python-api-core/commit/538df80ed6d21f43b512a73853935f7a7b9bdf52))
+
+## [2.10.0](https://github.com/googleapis/python-api-core/compare/v2.9.0...v2.10.0) (2022-09-02)
+
+
+### Features
+
+* Add 'strict' to flatten_query_params to lower-case bools ([#433](https://github.com/googleapis/python-api-core/issues/433)) ([83678e9](https://github.com/googleapis/python-api-core/commit/83678e94e1081f9087b19c43f26fad4774184d66))
+
+## [2.9.0](https://github.com/googleapis/python-api-core/compare/v2.8.2...v2.9.0) (2022-09-01)
+
+
+### Features
+
+* Make grpc transcode logic work in terms of protobuf python objects ([#428](https://github.com/googleapis/python-api-core/issues/428)) ([c3ad8ea](https://github.com/googleapis/python-api-core/commit/c3ad8ea67447e3d8a1154d7a9221e116f60d425a))
+
+
+### Bug Fixes
+
+* Require python 3.7+ ([#410](https://github.com/googleapis/python-api-core/issues/410)) ([7ddb8c0](https://github.com/googleapis/python-api-core/commit/7ddb8c00e6be7ab6905a9a802ad1c3063fbfa46c))
+* Restore support for grpcio-gcp ([#418](https://github.com/googleapis/python-api-core/issues/418)) ([8c19609](https://github.com/googleapis/python-api-core/commit/8c19609d6244930bd91fd5f40ef9b5b65584c4a5))
+
+## [2.8.2](https://github.com/googleapis/python-api-core/compare/v2.8.1...v2.8.2) (2022-06-13)
+
+
+### Bug Fixes
+
+* **deps:** allow protobuf < 5.0.0 ([#400](https://github.com/googleapis/python-api-core/issues/400)) ([8f73d2e](https://github.com/googleapis/python-api-core/commit/8f73d2ee2d3af2201f877aa7e2f7361147759dc7))
+* drop support for grpc-gcp ([#401](https://github.com/googleapis/python-api-core/issues/401)) ([5da6733](https://github.com/googleapis/python-api-core/commit/5da6733a475c436efc11b14889af73b3a0e20379))
+
+
+### Documentation
+
+* fix changelog header to consistent size ([#394](https://github.com/googleapis/python-api-core/issues/394)) ([ac266e9](https://github.com/googleapis/python-api-core/commit/ac266e935bc4e7c6dff250384407e7a60d8dba90))
+* Fix typo in the BackgroundConsumer docstring ([#395](https://github.com/googleapis/python-api-core/issues/395)) ([0eb727f](https://github.com/googleapis/python-api-core/commit/0eb727f92314db3c4383754514f75a49ba02e27b))
+
+## [2.8.1](https://github.com/googleapis/python-api-core/compare/v2.8.0...v2.8.1) (2022-05-26)
+
+
+### Bug Fixes
+
+* **deps:** require googleapis-common-protos >= 1.56.2 ([d84d66c](https://github.com/googleapis/python-api-core/commit/d84d66c2a4107f5f9a20c53e870a27fb1250ea3d))
+* **deps:** require protobuf>= 3.15.0, <4.0.0dev ([#385](https://github.com/googleapis/python-api-core/issues/385)) ([d84d66c](https://github.com/googleapis/python-api-core/commit/d84d66c2a4107f5f9a20c53e870a27fb1250ea3d))
+
+## [2.8.0](https://github.com/googleapis/python-api-core/compare/v2.7.3...v2.8.0) (2022-05-18)
+
+
+### Features
+
+* adds support for audience in client_options ([#379](https://github.com/googleapis/python-api-core/issues/379)) ([c97c498](https://github.com/googleapis/python-api-core/commit/c97c4980125a86f384cdf12720df7bb1a2adf9d2))
+* adds support for audience in client_options. ([c97c498](https://github.com/googleapis/python-api-core/commit/c97c4980125a86f384cdf12720df7bb1a2adf9d2))
+
+## [2.7.3](https://github.com/googleapis/python-api-core/compare/v2.7.2...v2.7.3) (2022-04-29)
+
+
+### Bug Fixes
+
+* Avoid AttributeError if grpcio-status is not installed ([#370](https://github.com/googleapis/python-api-core/issues/370)) ([022add1](https://github.com/googleapis/python-api-core/commit/022add16266f9c07f0f88eea13472cc2e0bfc991))
+
+## [2.7.2](https://github.com/googleapis/python-api-core/compare/v2.7.1...v2.7.2) (2022-04-13)
+
+
+### Bug Fixes
+
+* allow grpc without grpcio-status ([#355](https://github.com/googleapis/python-api-core/issues/355)) ([112049e](https://github.com/googleapis/python-api-core/commit/112049e79f5a5b0a989d85d438a1bd29485f46f7))
+* remove dependency on pkg_resources ([#361](https://github.com/googleapis/python-api-core/issues/361)) ([523dbd0](https://github.com/googleapis/python-api-core/commit/523dbd0b10d37ffcf83fa751f0bad313f162abf1))
+
+## [2.7.1](https://github.com/googleapis/python-api-core/compare/v2.7.0...v2.7.1) (2022-03-09)
+
+
+### Bug Fixes
+
+* add more context to error message. ([#340](https://github.com/googleapis/python-api-core/issues/340)) ([0680fb4](https://github.com/googleapis/python-api-core/commit/0680fb4d3e013fe2de27e0a2ae2cd9896479e596))
+
+## [2.7.0](https://github.com/googleapis/python-api-core/compare/v2.6.1...v2.7.0) (2022-03-08)
+
+
+### Features
+
+* expose extra fields in ExtendedOperation ([#351](https://github.com/googleapis/python-api-core/issues/351)) ([9abc6f4](https://github.com/googleapis/python-api-core/commit/9abc6f48f23c87b9771dca3c96b4f6af39620a50))
+
+## [2.6.1](https://github.com/googleapis/python-api-core/compare/v2.6.0...v2.6.1) (2022-03-05)
+
+
+### Bug Fixes
+
+* Remove py2 tag from wheel ([#343](https://github.com/googleapis/python-api-core/issues/343)) ([7e21e9e](https://github.com/googleapis/python-api-core/commit/7e21e9e34892472a34f9b44175fa761f0e3fd9ed))
+
+## [2.6.0](https://github.com/googleapis/python-api-core/compare/v2.5.0...v2.6.0) (2022-03-03)
+
+
+### Features
+
+* initial support for Extended Operations ([#344](https://github.com/googleapis/python-api-core/issues/344)) ([021bb7d](https://github.com/googleapis/python-api-core/commit/021bb7d5bf0a1d8ac58dbf0c738fac309135ba7d))
+
+## [2.5.0](https://github.com/googleapis/python-api-core/compare/v2.4.0...v2.5.0) (2022-02-02)
+
+
+### Features
+
+* add api_key to client options ([#248](https://github.com/googleapis/python-api-core/issues/248)) ([5e5ad37](https://github.com/googleapis/python-api-core/commit/5e5ad37b8161109d65b0fab43636f7424e570fa3))
+
+
+### Bug Fixes
+
+* **deps:** remove setuptools from dependencies ([#339](https://github.com/googleapis/python-api-core/issues/339)) ([c782f29](https://github.com/googleapis/python-api-core/commit/c782f294b50b078f01959627fb82aa4c5efec333))
+
+
+### Documentation
+
+* fix typo in library name ([#332](https://github.com/googleapis/python-api-core/issues/332)) ([f267111](https://github.com/googleapis/python-api-core/commit/f267111823545a6c67ef5f10b85cd8c2fab8a612))
+
+## [2.4.0](https://www.github.com/googleapis/python-api-core/compare/v2.3.2...v2.4.0) (2022-01-11)
+
+
+### Features
+
+* add support for 'error_info' ([#315](https://www.github.com/googleapis/python-api-core/issues/315)) ([cc46aa6](https://www.github.com/googleapis/python-api-core/commit/cc46aa68ec184871330d16a6c767f57a4f0eb633))
+* iterator for processing JSON responses in REST streaming. ([#317](https://www.github.com/googleapis/python-api-core/issues/317)) ([f9f2696](https://www.github.com/googleapis/python-api-core/commit/f9f26969842b456ea372bed941d712b7a9ab7239))
+
+## [2.3.2](https://www.github.com/googleapis/python-api-core/compare/v2.3.1...v2.3.2) (2021-12-16)
+
+
+### Bug Fixes
+
+* address broken wheels in version 2.3.1
+
+## [2.3.1](https://www.github.com/googleapis/python-api-core/compare/v2.3.0...v2.3.1) (2021-12-15)
+
+
+### Bug Fixes
+* exclude function target from retry deadline exceeded exception message ([#318](https://www.github.com/googleapis/python-api-core/issues/318)) ([34ebdcc](https://www.github.com/googleapis/python-api-core/commit/34ebdcc251d4f3d7d496e8e0b78847645a06650b))
+
+## [2.3.0](https://www.github.com/googleapis/python-api-core/compare/v2.2.2...v2.3.0) (2021-11-25)
+
+
+### Features
+
+* add operations rest client to support long-running operations. ([#311](https://www.github.com/googleapis/python-api-core/issues/311)) ([ce1adf3](https://www.github.com/googleapis/python-api-core/commit/ce1adf395982ede157c0f25a920946bb52789873))
+
+
+### Bug Fixes
+
+* handle bare 'grpc.Call' in 'from_grpc_error' ([#298](https://www.github.com/googleapis/python-api-core/issues/298)) ([060b339](https://www.github.com/googleapis/python-api-core/commit/060b339e3af296dd1772bfc1b4a0d2b4264cae1f))
+
+## [2.2.2](https://www.github.com/googleapis/python-api-core/compare/v2.2.1...v2.2.2) (2021-11-02)
+
+
+### Bug Fixes
+
+* make 'gapic_v1.method.DEFAULT' a typed object ([#292](https://www.github.com/googleapis/python-api-core/issues/292)) ([ffc51f0](https://www.github.com/googleapis/python-api-core/commit/ffc51f03c7ce5d9f009ba859b8df385d52925578))
+
+## [2.2.1](https://www.github.com/googleapis/python-api-core/compare/v2.2.0...v2.2.1) (2021-10-26)
+
+
+### Bug Fixes
+
+* revert "fix: do not error on LROs with no response or error" ([#294](https://www.github.com/googleapis/python-api-core/issues/294)) ([9e6091e](https://www.github.com/googleapis/python-api-core/commit/9e6091ee59a30e72a6278b369f6a08e7aef32f22))
+
+## [2.2.0](https://www.github.com/googleapis/python-api-core/compare/v2.1.1...v2.2.0) (2021-10-25)
+
+
+### Features
+
+* add 'GoogleAPICallError.error_details' property ([#286](https://www.github.com/googleapis/python-api-core/issues/286)) ([ef6f0fc](https://www.github.com/googleapis/python-api-core/commit/ef6f0fcfdfe771172056e35e3c990998b3b00416))
+
+## [2.1.1](https://www.github.com/googleapis/python-api-core/compare/v2.1.0...v2.1.1) (2021-10-13)
+
+
+### Bug Fixes
+
+* add mypy checking + 'py.typed' file ([#290](https://www.github.com/googleapis/python-api-core/issues/290)) ([0023ee1](https://www.github.com/googleapis/python-api-core/commit/0023ee1fe0e8b80c7a9e8987e0f322a829e5d613))
+
+## [2.1.0](https://www.github.com/googleapis/python-api-core/compare/v2.0.1...v2.1.0) (2021-10-05)
+
+
+### Features
+
+* add grpc transcoding + tests ([#259](https://www.github.com/googleapis/python-api-core/issues/259)) ([afe0fa1](https://www.github.com/googleapis/python-api-core/commit/afe0fa14c21289c8244606a9f81544cff8ac5f7c))
+* Add helper function to format query_params for rest transport. ([#275](https://www.github.com/googleapis/python-api-core/issues/275)) ([1c5eb4d](https://www.github.com/googleapis/python-api-core/commit/1c5eb4df93d78e791082d9282330ebf0faacd222))
+* add support for Python 3.10 ([#284](https://www.github.com/googleapis/python-api-core/issues/284)) ([a422a5d](https://www.github.com/googleapis/python-api-core/commit/a422a5d72cb6f363d57e7a4effe421ba8e049cde))
+
+## [2.0.1](https://www.github.com/googleapis/python-api-core/compare/v2.0.0...v2.0.1) (2021-08-31)
+
+
+### Bug Fixes
+
+* do not error on LROs with no response or error ([#258](https://www.github.com/googleapis/python-api-core/issues/258)) ([618f192](https://www.github.com/googleapis/python-api-core/commit/618f19201af729205892fcecd9c8e315ba3174a3))
+
+## [2.0.0](https://www.github.com/googleapis/python-api-core/compare/v2.0.0-b1...v2.0.0) (2021-08-18)
+
+### ⚠ BREAKING CHANGES
+
+* drop support for Python 2.7 / 3.5 ([#212](https://www.github.com/googleapis/python-api-core/issues/212)) ([a30f004](https://www.github.com/googleapis/python-api-core/commit/a30f004e74f709d46e905dd819c71f43354e9ac9))
+
+### Bug Fixes
+
+* bump grpcio version to use stable aio API ([#234](https://www.github.com/googleapis/python-api-core/issues/234)) ([bdbf889](https://www.github.com/googleapis/python-api-core/commit/bdbf889210b709d7c1945f2160bcba9161b4dd2e))
+* strip trailing _ from field mask paths ([#228](https://www.github.com/googleapis/python-api-core/issues/228)) ([ff6ef1b](https://www.github.com/googleapis/python-api-core/commit/ff6ef1bd07fa68307b7c82c910416d770e7b3416))
+
 ## [2.0.0b1](https://www.github.com/googleapis/python-api-core/compare/v1.31.1...v2.0.0b1) (2021-08-03)
 
 
@@ -15,7 +452,7 @@
 
 * strip trailing _ from field mask paths ([#228](https://www.github.com/googleapis/python-api-core/issues/228)) ([ff6ef1b](https://www.github.com/googleapis/python-api-core/commit/ff6ef1bd07fa68307b7c82c910416d770e7b3416))
 
-### [1.31.1](https://www.github.com/googleapis/python-api-core/compare/v1.31.0...v1.31.1) (2021-07-26)
+## [1.31.1](https://www.github.com/googleapis/python-api-core/compare/v1.31.0...v1.31.1) (2021-07-26)
 
 
 ### Bug Fixes
@@ -78,7 +515,7 @@
 * Add support for `rest/` token in `x-goog-api-client` header ([#189](https://www.github.com/googleapis/python-api-core/issues/189)) ([15aca6b](https://www.github.com/googleapis/python-api-core/commit/15aca6b288b2ec5ce0251e442e1dfa7f52e1b124))
 * retry google.auth TransportError and requests ConnectionError ([#178](https://www.github.com/googleapis/python-api-core/issues/178)) ([6ae04a8](https://www.github.com/googleapis/python-api-core/commit/6ae04a8d134fffe13f06081e15f9723c1b2ea334))
 
-### [1.26.3](https://www.github.com/googleapis/python-api-core/compare/v1.26.2...v1.26.3) (2021-03-25)
+## [1.26.3](https://www.github.com/googleapis/python-api-core/compare/v1.26.2...v1.26.3) (2021-03-25)
 
 
 ### Bug Fixes
@@ -90,14 +527,14 @@
 
 * update python contributing guide ([#147](https://www.github.com/googleapis/python-api-core/issues/147)) ([1d76b57](https://www.github.com/googleapis/python-api-core/commit/1d76b57d1f218f7885f85dc7c052bad1ad3857ac))
 
-### [1.26.2](https://www.github.com/googleapis/python-api-core/compare/v1.26.1...v1.26.2) (2021-03-23)
+## [1.26.2](https://www.github.com/googleapis/python-api-core/compare/v1.26.1...v1.26.2) (2021-03-23)
 
 
 ### Bug Fixes
 
 * save empty IAM policy bindings ([#155](https://www.github.com/googleapis/python-api-core/issues/155)) ([536c2ca](https://www.github.com/googleapis/python-api-core/commit/536c2cad814b8fa8cd346a3d7bd5f6b9889c4a6f))
 
-### [1.26.1](https://www.github.com/googleapis/python-api-core/compare/v1.26.0...v1.26.1) (2021-02-12)
+## [1.26.1](https://www.github.com/googleapis/python-api-core/compare/v1.26.0...v1.26.1) (2021-02-12)
 
 
 ### Bug Fixes
@@ -111,7 +548,7 @@
 
 * allow default_host and default_scopes to be passed to create_channel ([#134](https://www.github.com/googleapis/python-api-core/issues/134)) ([94c76e0](https://www.github.com/googleapis/python-api-core/commit/94c76e0873e5b2f42331d5b1ad286c1e63b61395))
 
-### [1.25.1](https://www.github.com/googleapis/python-api-core/compare/v1.25.0...v1.25.1) (2021-01-25)
+## [1.25.1](https://www.github.com/googleapis/python-api-core/compare/v1.25.0...v1.25.1) (2021-01-25)
 
 
 ### Bug Fixes
@@ -135,7 +572,7 @@
 
 * **python:** document adding Python 3.9 support, dropping 3.5 support ([#120](https://www.github.com/googleapis/python-api-core/issues/120)) ([b51b7f5](https://www.github.com/googleapis/python-api-core/commit/b51b7f587042fe9340371c1b5c8e9adf8001c43a)), closes [#787](https://www.github.com/googleapis/python-api-core/issues/787)
 
-### [1.24.1](https://www.github.com/googleapis/python-api-core/compare/v1.24.0...v1.24.1) (2020-12-16)
+## [1.24.1](https://www.github.com/googleapis/python-api-core/compare/v1.24.0...v1.24.1) (2020-12-16)
 
 
 ### Bug Fixes
@@ -168,28 +605,28 @@
 * harden install to use full paths, and windows separators on windows ([#88](https://www.github.com/googleapis/python-api-core/issues/88)) ([db8e636](https://www.github.com/googleapis/python-api-core/commit/db8e636f545a8872f959e3f403cfec30ffed6c34))
 * update out-of-date comment in exceptions.py ([#93](https://www.github.com/googleapis/python-api-core/issues/93)) ([70ebe42](https://www.github.com/googleapis/python-api-core/commit/70ebe42601b3d088b3421233ef7d8245229b7265))
 
-### [1.22.4](https://www.github.com/googleapis/python-api-core/compare/v1.22.3...v1.22.4) (2020-10-05)
+## [1.22.4](https://www.github.com/googleapis/python-api-core/compare/v1.22.3...v1.22.4) (2020-10-05)
 
 
 ### Bug Fixes
 
 * use version.py instead of pkg_resources.get_distribution ([#80](https://www.github.com/googleapis/python-api-core/issues/80)) ([d480d97](https://www.github.com/googleapis/python-api-core/commit/d480d97e41cd6705325b3b649360553a83c23f47))
 
-### [1.22.3](https://www.github.com/googleapis/python-api-core/compare/v1.22.2...v1.22.3) (2020-10-02)
+## [1.22.3](https://www.github.com/googleapis/python-api-core/compare/v1.22.2...v1.22.3) (2020-10-02)
 
 
 ### Bug Fixes
 
 * **deps:** require six >= 1.13.0 ([#78](https://www.github.com/googleapis/python-api-core/issues/78)) ([a7a8b98](https://www.github.com/googleapis/python-api-core/commit/a7a8b98602a3eb277fdc607ac69f3bcb147f3351)), closes [/github.com/benjaminp/six/blob/c0be8815d13df45b6ae471c4c436cce8c192245d/CHANGES#L30-L31](https://www.github.com/googleapis//github.com/benjaminp/six/blob/c0be8815d13df45b6ae471c4c436cce8c192245d/CHANGES/issues/L30-L31)
 
-### [1.22.2](https://www.github.com/googleapis/python-api-core/compare/v1.22.1...v1.22.2) (2020-09-03)
+## [1.22.2](https://www.github.com/googleapis/python-api-core/compare/v1.22.1...v1.22.2) (2020-09-03)
 
 
 ### Bug Fixes
 
 * only add quota project id if supported ([#75](https://www.github.com/googleapis/python-api-core/issues/75)) ([8f8ee78](https://www.github.com/googleapis/python-api-core/commit/8f8ee7879e4f834f3c676e535ffc41b5b9b2de62))
 
-### [1.22.1](https://www.github.com/googleapis/python-api-core/compare/v1.22.0...v1.22.1) (2020-08-12)
+## [1.22.1](https://www.github.com/googleapis/python-api-core/compare/v1.22.0...v1.22.1) (2020-08-12)
 
 
 ### Documentation
@@ -220,7 +657,7 @@
 
 * allow credentials files to be passed for channel creation ([#50](https://www.github.com/googleapis/python-api-core/issues/50)) ([ded92d0](https://www.github.com/googleapis/python-api-core/commit/ded92d0acdcde4295d0e5df05fda0d83783a3991))
 
-### [1.20.1](https://www.github.com/googleapis/python-api-core/compare/v1.20.0...v1.20.1) (2020-06-16)
+## [1.20.1](https://www.github.com/googleapis/python-api-core/compare/v1.20.0...v1.20.1) (2020-06-16)
 
 
 ### Bug Fixes
@@ -234,7 +671,7 @@
 
 * allow disabling response stream pre-fetch ([#30](https://www.github.com/googleapis/python-api-core/issues/30)) ([74e0b0f](https://www.github.com/googleapis/python-api-core/commit/74e0b0f8387207933c120af15b2bb5d175dd8f84)), closes [#25](https://www.github.com/googleapis/python-api-core/issues/25)
 
-### [1.19.1](https://www.github.com/googleapis/python-api-core/compare/v1.19.0...v1.19.1) (2020-06-06)
+## [1.19.1](https://www.github.com/googleapis/python-api-core/compare/v1.19.0...v1.19.1) (2020-06-06)
 
 
 ### Bug Fixes
diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 358404f2..1a1f608b 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -21,7 +21,7 @@ In order to add a feature:
   documentation.
 
 - The feature must work fully on the following CPython versions:
-  3.6, 3.7, 3.8 and 3.9 on both UNIX and Windows.
+  3.7, 3.8, 3.9, 3.10, 3.11, 3.12 and 3.13 on both UNIX and Windows.
 
 - The feature must not add unnecessary dependencies (where
   "unnecessary" is of course subjective, but new dependencies should
@@ -49,9 +49,9 @@ You'll have to create a development environment using a Git checkout:
    # Configure remotes such that you can pull changes from the googleapis/python-api-core
    # repository into your local repository.
    $ git remote add upstream git@github.com:googleapis/python-api-core.git
-   # fetch and merge changes from upstream into master
+   # fetch and merge changes from upstream into main
    $ git fetch upstream
-   $ git merge upstream/master
+   $ git merge upstream/main
 
 Now your local repo is set up such that you will push changes to your GitHub
 repo, from which you can submit a pull request.
@@ -71,7 +71,7 @@ We use `nox <https://nox.readthedocs.io/en/latest/>`__ to instrument our tests.
 
 - To run a single unit test::
 
-    $ nox -s unit-3.9 -- -k <name of test>
+    $ nox -s unit-3.13 -- -k <name of test>
 
 
   .. note::
@@ -109,12 +109,12 @@ Coding Style
   variables::
 
    export GOOGLE_CLOUD_TESTING_REMOTE="upstream"
-   export GOOGLE_CLOUD_TESTING_BRANCH="master"
+   export GOOGLE_CLOUD_TESTING_BRANCH="main"
 
   By doing this, you are specifying the location of the most up-to-date
   version of ``python-api-core``. The the suggested remote name ``upstream``
   should point to the official ``googleapis`` checkout and the
-  the branch should be the main branch on that remote (``master``).
+  the branch should be the main branch on that remote (``main``).
 
 - This repository contains configuration for the
   `pre-commit <https://pre-commit.com/>`__ tool, which automates checking
@@ -185,7 +185,7 @@ The `description on PyPI`_ for the project comes directly from the
 ``README``. Due to the reStructuredText (``rst``) parser used by
 PyPI, relative links which will work on GitHub (e.g. ``CONTRIBUTING.rst``
 instead of
-``https://github.com/googleapis/python-api-core/blob/master/CONTRIBUTING.rst``)
+``https://github.com/googleapis/python-api-core/blob/main/CONTRIBUTING.rst``)
 may cause problems creating links or rendering the description.
 
 .. _description on PyPI: https://pypi.org/project/google-api-core
@@ -197,34 +197,28 @@ Supported Python Versions
 
 We support:
 
--  `Python 3.6`_
 -  `Python 3.7`_
 -  `Python 3.8`_
 -  `Python 3.9`_
+-  `Python 3.10`_
+-  `Python 3.11`_
+-  `Python 3.12`_
+-  `Python 3.13`_
 
-.. _Python 3.6: https://docs.python.org/3.6/
 .. _Python 3.7: https://docs.python.org/3.7/
 .. _Python 3.8: https://docs.python.org/3.8/
 .. _Python 3.9: https://docs.python.org/3.9/
+.. _Python 3.10: https://docs.python.org/3.10/
+.. _Python 3.11: https://docs.python.org/3.11/
+.. _Python 3.12: https://docs.python.org/3.12/
+.. _Python 3.13: https://docs.python.org/3.13/
 
 
 Supported versions can be found in our ``noxfile.py`` `config`_.
 
-.. _config: https://github.com/googleapis/python-api-core/blob/master/noxfile.py
+.. _config: https://github.com/googleapis/python-api-core/blob/main/noxfile.py
 
 
-We also explicitly decided to support Python 3 beginning with version 3.6.
-Reasons for this include:
-
--  Encouraging use of newest versions of Python 3
--  Taking the lead of `prominent`_ open-source `projects`_
--  `Unicode literal support`_ which allows for a cleaner codebase that
-   works in both Python 2 and Python 3
-
-.. _prominent: https://docs.djangoproject.com/en/1.9/faq/install/#what-python-version-can-i-use-with-django
-.. _projects: http://flask.pocoo.org/docs/0.10/python3/
-.. _Unicode literal support: https://www.python.org/dev/peps/pep-0414/
-
 **********
 Versioning
 **********
diff --git a/MANIFEST.in b/MANIFEST.in
index e783f4c6..d6814cd6 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 #
-# Copyright 2020 Google LLC
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/README.rst b/README.rst
index d94f3e88..58ae26cb 100644
--- a/README.rst
+++ b/README.rst
@@ -16,13 +16,16 @@ common helpers used by all Google API clients. For more information, see the
 
 Supported Python Versions
 -------------------------
-Python >= 3.6
+Python >= 3.7
 
 
 Unsupported Python Versions
 ---------------------------
 
-Python == 2.7, Python == 3.5.
+Python == 2.7, Python == 3.5, Python == 3.6.
 
 The last version of this library compatible with Python 2.7 and 3.5 is
-`google-api_core==1.31.1`.
+`google-api-core==1.31.1`.
+
+The last version of this library compatible with Python 3.6 is
+`google-api-core==2.8.2`.
diff --git a/docs/auth.rst b/docs/auth.rst
index a9b296d4..3dcc5fd3 100644
--- a/docs/auth.rst
+++ b/docs/auth.rst
@@ -165,7 +165,7 @@ possible to call Google Cloud APIs with a user account via
     getting started with the ``google-cloud-*`` library.
 
 The simplest way to use credentials from a user account is via
-Application Default Credentials using ``gcloud auth login``
+Application Default Credentials using ``gcloud auth application-default login``
 (as mentioned above) and :func:`google.auth.default`:
 
 .. code:: python
diff --git a/docs/conf.py b/docs/conf.py
index aec958f3..ad4723c0 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-# Copyright 2021 Google LLC
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -76,8 +76,8 @@
 # The encoding of source files.
 # source_encoding = 'utf-8-sig'
 
-# The master toctree document.
-master_doc = "index"
+# The root toctree document.
+root_doc = "index"
 
 # General information about the project.
 project = "google-api-core"
@@ -280,7 +280,7 @@
 #  author, documentclass [howto, manual, or own class]).
 latex_documents = [
     (
-        master_doc,
+        root_doc,
         "google-api-core.tex",
         "google-api-core Documentation",
         author,
@@ -314,7 +314,13 @@
 # One entry per manual page. List of tuples
 # (source start file, name, description, authors, manual section).
 man_pages = [
-    (master_doc, "google-api-core", "google-api-core Documentation", [author], 1,)
+    (
+        root_doc,
+        "google-api-core",
+        "google-api-core Documentation",
+        [author],
+        1,
+    )
 ]
 
 # If true, show URL addresses after external links.
@@ -328,7 +334,7 @@
 #  dir menu entry, description, category)
 texinfo_documents = [
     (
-        master_doc,
+        root_doc,
         "google-api-core",
         "google-api-core Documentation",
         author,
@@ -355,7 +361,10 @@
 intersphinx_mapping = {
     "python": ("https://python.readthedocs.org/en/latest/", None),
     "google-auth": ("https://googleapis.dev/python/google-auth/latest/", None),
-    "google.api_core": ("https://googleapis.dev/python/google-api-core/latest/", None,),
+    "google.api_core": (
+        "https://googleapis.dev/python/google-api-core/latest/",
+        None,
+    ),
     "grpc": ("https://grpc.github.io/grpc/python/", None),
     "proto-plus": ("https://proto-plus-python.readthedocs.io/en/latest/", None),
     "protobuf": ("https://googleapis.dev/python/protobuf/latest/", None),
diff --git a/docs/retry.rst b/docs/retry.rst
index 97a7f2ca..6e165f56 100644
--- a/docs/retry.rst
+++ b/docs/retry.rst
@@ -10,4 +10,5 @@ Retry in AsyncIO
 
 .. automodule:: google.api_core.retry_async
   :members:
+  :noindex:
   :show-inheritance:
diff --git a/google/api_core/__init__.py b/google/api_core/__init__.py
index 605dd8be..b80ea372 100644
--- a/google/api_core/__init__.py
+++ b/google/api_core/__init__.py
@@ -14,7 +14,7 @@
 
 """Google API Core.
 
-This package contains common code and utilties used by Google client libraries.
+This package contains common code and utilities used by Google client libraries.
 """
 
 from google.api_core import version as api_core_version
diff --git a/google/api_core/_rest_streaming_base.py b/google/api_core/_rest_streaming_base.py
new file mode 100644
index 00000000..3bc87a96
--- /dev/null
+++ b/google/api_core/_rest_streaming_base.py
@@ -0,0 +1,118 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helpers for server-side streaming in REST."""
+
+from collections import deque
+import string
+from typing import Deque, Union
+import types
+
+import proto
+import google.protobuf.message
+from google.protobuf.json_format import Parse
+
+
+class BaseResponseIterator:
+    """Base Iterator over REST API responses. This class should not be used directly.
+
+    Args:
+        response_message_cls (Union[proto.Message, google.protobuf.message.Message]): A response
+        class expected to be returned from an API.
+
+    Raises:
+        ValueError: If `response_message_cls` is not a subclass of `proto.Message` or `google.protobuf.message.Message`.
+    """
+
+    def __init__(
+        self,
+        response_message_cls: Union[proto.Message, google.protobuf.message.Message],
+    ):
+        self._response_message_cls = response_message_cls
+        # Contains a list of JSON responses ready to be sent to user.
+        self._ready_objs: Deque[str] = deque()
+        # Current JSON response being built.
+        self._obj = ""
+        # Keeps track of the nesting level within a JSON object.
+        self._level = 0
+        # Keeps track whether HTTP response is currently sending values
+        # inside of a string value.
+        self._in_string = False
+        # Whether an escape symbol "\" was encountered.
+        self._escape_next = False
+
+        self._grab = types.MethodType(self._create_grab(), self)
+
+    def _process_chunk(self, chunk: str):
+        if self._level == 0:
+            if chunk[0] != "[":
+                raise ValueError(
+                    "Can only parse array of JSON objects, instead got %s" % chunk
+                )
+        for char in chunk:
+            if char == "{":
+                if self._level == 1:
+                    # Level 1 corresponds to the outermost JSON object
+                    # (i.e. the one we care about).
+                    self._obj = ""
+                if not self._in_string:
+                    self._level += 1
+                self._obj += char
+            elif char == "}":
+                self._obj += char
+                if not self._in_string:
+                    self._level -= 1
+                if not self._in_string and self._level == 1:
+                    self._ready_objs.append(self._obj)
+            elif char == '"':
+                # Helps to deal with an escaped quotes inside of a string.
+                if not self._escape_next:
+                    self._in_string = not self._in_string
+                self._obj += char
+            elif char in string.whitespace:
+                if self._in_string:
+                    self._obj += char
+            elif char == "[":
+                if self._level == 0:
+                    self._level += 1
+                else:
+                    self._obj += char
+            elif char == "]":
+                if self._level == 1:
+                    self._level -= 1
+                else:
+                    self._obj += char
+            else:
+                self._obj += char
+            self._escape_next = not self._escape_next if char == "\\" else False
+
+    def _create_grab(self):
+        if issubclass(self._response_message_cls, proto.Message):
+
+            def grab(this):
+                return this._response_message_cls.from_json(
+                    this._ready_objs.popleft(), ignore_unknown_fields=True
+                )
+
+            return grab
+        elif issubclass(self._response_message_cls, google.protobuf.message.Message):
+
+            def grab(this):
+                return Parse(this._ready_objs.popleft(), this._response_message_cls())
+
+            return grab
+        else:
+            raise ValueError(
+                "Response message class must be a subclass of proto.Message or google.protobuf.message.Message."
+            )
diff --git a/google/api_core/bidi.py b/google/api_core/bidi.py
index 56a021a9..b002b409 100644
--- a/google/api_core/bidi.py
+++ b/google/api_core/bidi.py
@@ -91,11 +91,9 @@ def __init__(self, queue, period=1, initial_request=None):
     def _is_active(self):
         # Note: there is a possibility that this starts *before* the call
         # property is set. So we have to check if self.call is set before
-        # seeing if it's active.
-        if self.call is not None and not self.call.is_active():
-            return False
-        else:
-            return True
+        # seeing if it's active. We need to return True if self.call is None.
+        # See https://github.com/googleapis/python-api-core/issues/560.
+        return self.call is None or self.call.is_active()
 
     def __iter__(self):
         if self._initial_request is not None:
@@ -265,6 +263,10 @@ def add_done_callback(self, callback):
         self._callbacks.append(callback)
 
     def _on_call_done(self, future):
+        # This occurs when the RPC errors or is successfully terminated.
+        # Note that grpc's "future" here can also be a grpc.RpcError.
+        # See note in https://github.com/grpc/grpc/issues/10885#issuecomment-302651331
+        # that `grpc.RpcError` is also `grpc.call`.
         for callback in self._callbacks:
             callback(future)
 
@@ -276,7 +278,13 @@ def open(self):
         request_generator = _RequestQueueGenerator(
             self._request_queue, initial_request=self._initial_request
         )
-        call = self._start_rpc(iter(request_generator), metadata=self._rpc_metadata)
+        try:
+            call = self._start_rpc(iter(request_generator), metadata=self._rpc_metadata)
+        except exceptions.GoogleAPICallError as exc:
+            # The original `grpc.RpcError` (which is usually also a `grpc.Call`) is
+            # available from the ``response`` property on the mapped exception.
+            self._on_call_done(exc.response)
+            raise
 
         request_generator.call = call
 
@@ -298,6 +306,8 @@ def close(self):
         self._request_queue.put(None)
         self.call.cancel()
         self._request_generator = None
+        self._initial_request = None
+        self._callbacks = []
         # Don't set self.call to None. Keep it around so that send/recv can
         # raise the error.
 
@@ -364,7 +374,7 @@ class ResumableBidiRpc(BidiRpc):
         def should_recover(exc):
             return (
                 isinstance(exc, grpc.RpcError) and
-                exc.code() == grpc.StatusCode.UNVAILABLE)
+                exc.code() == grpc.StatusCode.UNAVAILABLE)
 
         initial_request = example_pb2.StreamingRpcRequest(
             setting='example')
@@ -589,7 +599,7 @@ class BackgroundConsumer(object):
         def should_recover(exc):
             return (
                 isinstance(exc, grpc.RpcError) and
-                exc.code() == grpc.StatusCode.UNVAILABLE)
+                exc.code() == grpc.StatusCode.UNAVAILABLE)
 
         initial_request = example_pb2.StreamingRpcRequest(
             setting='example')
@@ -654,7 +664,8 @@ def _thread_main(self, ready):
                 _LOGGER.debug("waiting for recv.")
                 response = self._bidi_rpc.recv()
                 _LOGGER.debug("recved response.")
-                self._on_response(response)
+                if self._on_response is not None:
+                    self._on_response(response)
 
         except exceptions.GoogleAPICallError as exc:
             _LOGGER.debug(
@@ -709,6 +720,7 @@ def stop(self):
                     _LOGGER.warning("Background thread did not exit.")
 
             self._thread = None
+            self._on_response = None
 
     @property
     def is_active(self):
@@ -727,7 +739,7 @@ def resume(self):
         """Resumes the response stream."""
         with self._wake:
             self._paused = False
-            self._wake.notifyAll()
+            self._wake.notify_all()
 
     @property
     def is_paused(self):
diff --git a/google/api_core/client_info.py b/google/api_core/client_info.py
index d7f4367a..90926beb 100644
--- a/google/api_core/client_info.py
+++ b/google/api_core/client_info.py
@@ -19,17 +19,20 @@
 """
 
 import platform
-
-import pkg_resources
+from typing import Union
 
 from google.api_core import version as api_core_version
 
 _PY_VERSION = platform.python_version()
 _API_CORE_VERSION = api_core_version.__version__
 
+_GRPC_VERSION: Union[str, None]
+
 try:
-    _GRPC_VERSION = pkg_resources.get_distribution("grpcio").version
-except pkg_resources.DistributionNotFound:  # pragma: NO COVER
+    import grpc
+
+    _GRPC_VERSION = grpc.__version__
+except ImportError:  # pragma: NO COVER
     _GRPC_VERSION = None
 
 
@@ -45,7 +48,7 @@ class ClientInfo(object):
             ``'3.9.6'``.
         grpc_version (Optional[str]): The gRPC library version.
         api_core_version (str): The google-api-core library version.
-        gapic_version (Optional[str]): The sversion of gapic-generated client
+        gapic_version (Optional[str]): The version of gapic-generated client
             library, if the library was generated by gapic.
         client_library_version (Optional[str]): The version of the client
             library, generally used if the client library was not generated
@@ -54,7 +57,8 @@ class ClientInfo(object):
         user_agent (Optional[str]): Prefix to the user agent header. This is
             used to supply information such as application name or partner tool.
             Recommended format: ``application-or-tool-ID/major.minor.version``.
-        rest_version (Optional[str]): The requests library version.
+        rest_version (Optional[str]): A string with labeled versions of the
+            dependencies used for REST transport.
     """
 
     def __init__(
diff --git a/google/api_core/client_logging.py b/google/api_core/client_logging.py
new file mode 100644
index 00000000..837e3e0c
--- /dev/null
+++ b/google/api_core/client_logging.py
@@ -0,0 +1,144 @@
+import logging
+import json
+import os
+
+from typing import List, Optional
+
+_LOGGING_INITIALIZED = False
+_BASE_LOGGER_NAME = "google"
+
+# Fields to be included in the StructuredLogFormatter.
+#
+# TODO(https://github.com/googleapis/python-api-core/issues/761): Update this list to support additional logging fields.
+_recognized_logging_fields = [
+    "httpRequest",
+    "rpcName",
+    "serviceName",
+    "credentialsType",
+    "credentialsInfo",
+    "universeDomain",
+    "request",
+    "response",
+    "metadata",
+    "retryAttempt",
+    "httpResponse",
+]  # Additional fields to be Logged.
+
+
+def logger_configured(logger) -> bool:
+    """Determines whether `logger` has non-default configuration
+
+    Args:
+      logger: The logger to check.
+
+    Returns:
+      bool: Whether the logger has any non-default configuration.
+    """
+    return (
+        logger.handlers != [] or logger.level != logging.NOTSET or not logger.propagate
+    )
+
+
+def initialize_logging():
+    """Initializes "google" loggers, partly based on the environment variable
+
+    Initializes the "google" logger and any loggers (at the "google"
+    level or lower) specified by the environment variable
+    GOOGLE_SDK_PYTHON_LOGGING_SCOPE, as long as none of these loggers
+    were previously configured. If any such loggers (including the
+    "google" logger) are initialized, they are set to NOT propagate
+    log events up to their parent loggers.
+
+    This initialization is executed only once, and hence the
+    environment variable is only processed the first time this
+    function is called.
+    """
+    global _LOGGING_INITIALIZED
+    if _LOGGING_INITIALIZED:
+        return
+    scopes = os.getenv("GOOGLE_SDK_PYTHON_LOGGING_SCOPE", "")
+    setup_logging(scopes)
+    _LOGGING_INITIALIZED = True
+
+
+def parse_logging_scopes(scopes: Optional[str] = None) -> List[str]:
+    """Returns a list of logger names.
+
+    Splits the single string of comma-separated logger names into a list of individual logger name strings.
+
+    Args:
+      scopes: The name of a single logger. (In the future, this will be a comma-separated list of multiple loggers.)
+
+    Returns:
+      A list of all the logger names in scopes.
+    """
+    if not scopes:
+        return []
+    # TODO(https://github.com/googleapis/python-api-core/issues/759): check if the namespace is a valid namespace.
+    # TODO(b/380481951): Support logging multiple scopes.
+    # TODO(b/380483756): Raise or log a warning for an invalid scope.
+    namespaces = [scopes]
+    return namespaces
+
+
+def configure_defaults(logger):
+    """Configures `logger` to emit structured info to stdout."""
+    if not logger_configured(logger):
+        console_handler = logging.StreamHandler()
+        logger.setLevel("DEBUG")
+        logger.propagate = False
+        formatter = StructuredLogFormatter()
+        console_handler.setFormatter(formatter)
+        logger.addHandler(console_handler)
+
+
+def setup_logging(scopes: str = ""):
+    """Sets up logging for the specified `scopes`.
+
+    If the loggers specified in `scopes` have not been previously
+    configured, this will configure them to emit structured log
+    entries to stdout, and to not propagate their log events to their
+    parent loggers. Additionally, if the "google" logger (whether it
+    was specified in `scopes` or not) was not previously configured,
+    it will also configure it to not propagate log events to the root
+    logger.
+
+    Args:
+      scopes: The name of a single logger. (In the future, this will be a comma-separated list of multiple loggers.)
+
+    """
+
+    # only returns valid logger scopes (namespaces)
+    # this list has at most one element.
+    logger_names = parse_logging_scopes(scopes)
+
+    for namespace in logger_names:
+        # This will either create a module level logger or get the reference of the base logger instantiated above.
+        logger = logging.getLogger(namespace)
+
+        # Configure default settings.
+        configure_defaults(logger)
+
+    # disable log propagation at base logger level to the root logger only if a base logger is not already configured via code changes.
+    base_logger = logging.getLogger(_BASE_LOGGER_NAME)
+    if not logger_configured(base_logger):
+        base_logger.propagate = False
+
+
+# TODO(https://github.com/googleapis/python-api-core/issues/763): Expand documentation.
+class StructuredLogFormatter(logging.Formatter):
+    # TODO(https://github.com/googleapis/python-api-core/issues/761): ensure that additional fields such as
+    # function name, file name, and line no. appear in a log output.
+    def format(self, record: logging.LogRecord):
+        log_obj = {
+            "timestamp": self.formatTime(record),
+            "severity": record.levelname,
+            "name": record.name,
+            "message": record.getMessage(),
+        }
+
+        for field_name in _recognized_logging_fields:
+            value = getattr(record, field_name, None)
+            if value is not None:
+                log_obj[field_name] = value
+        return json.dumps(log_obj)
diff --git a/google/api_core/client_options.py b/google/api_core/client_options.py
index be5523df..d11665d2 100644
--- a/google/api_core/client_options.py
+++ b/google/api_core/client_options.py
@@ -48,6 +48,8 @@ def get_client_cert():
 
 """
 
+from typing import Callable, Mapping, Optional, Sequence, Tuple
+
 
 class ClientOptions(object):
     """Client Options used to set options on clients.
@@ -55,49 +57,84 @@ class ClientOptions(object):
     Args:
         api_endpoint (Optional[str]): The desired API endpoint, e.g.,
             compute.googleapis.com
-        client_cert_source (Optional[Callable[[], (bytes, bytes)]]): A callback
+        client_cert_source (Optional[Callable[[], Tuple[bytes, bytes]]]): A callback
             which returns client certificate bytes and private key bytes both in
             PEM format. ``client_cert_source`` and ``client_encrypted_cert_source``
             are mutually exclusive.
-        client_encrypted_cert_source (Optional[Callable[[], (str, str, bytes)]]):
+        client_encrypted_cert_source (Optional[Callable[[], Tuple[str, str, bytes]]]):
             A callback which returns client certificate file path, encrypted
             private key file path, and the passphrase bytes.``client_cert_source``
             and ``client_encrypted_cert_source`` are mutually exclusive.
         quota_project_id (Optional[str]): A project name that a client's
             quota belongs to.
         credentials_file (Optional[str]): A path to a file storing credentials.
+            ``credentials_file` and ``api_key`` are mutually exclusive.
+
+            .. warning::
+                Important: If you accept a credential configuration (credential JSON/File/Stream)
+                from an external source for authentication to Google Cloud Platform, you must
+                validate it before providing it to any Google API or client library. Providing an
+                unvalidated credential configuration to Google APIs or libraries can compromise
+                the security of your systems and data. For more information, refer to
+                `Validate credential configurations from external sources`_.
+
+            .. _Validate credential configurations from external sources:
+
+            https://cloud.google.com/docs/authentication/external/externally-sourced-credentials
         scopes (Optional[Sequence[str]]): OAuth access token override scopes.
+        api_key (Optional[str]): Google API key. ``credentials_file`` and
+            ``api_key`` are mutually exclusive.
+        api_audience (Optional[str]): The intended audience for the API calls
+            to the service that will be set when using certain 3rd party
+            authentication flows. Audience is typically a resource identifier.
+            If not set, the service endpoint value will be used as a default.
+            An example of a valid ``api_audience`` is: "https://language.googleapis.com".
+        universe_domain (Optional[str]): The desired universe domain. This must match
+            the one in credentials. If not set, the default universe domain is
+            `googleapis.com`. If both `api_endpoint` and `universe_domain` are set,
+            then `api_endpoint` is used as the service endpoint. If `api_endpoint` is
+            not specified, the format will be `{service}.{universe_domain}`.
 
     Raises:
         ValueError: If both ``client_cert_source`` and ``client_encrypted_cert_source``
-            are provided.
+            are provided, or both ``credentials_file`` and ``api_key`` are provided.
     """
 
     def __init__(
         self,
-        api_endpoint=None,
-        client_cert_source=None,
-        client_encrypted_cert_source=None,
-        quota_project_id=None,
-        credentials_file=None,
-        scopes=None,
+        api_endpoint: Optional[str] = None,
+        client_cert_source: Optional[Callable[[], Tuple[bytes, bytes]]] = None,
+        client_encrypted_cert_source: Optional[
+            Callable[[], Tuple[str, str, bytes]]
+        ] = None,
+        quota_project_id: Optional[str] = None,
+        credentials_file: Optional[str] = None,
+        scopes: Optional[Sequence[str]] = None,
+        api_key: Optional[str] = None,
+        api_audience: Optional[str] = None,
+        universe_domain: Optional[str] = None,
     ):
         if client_cert_source and client_encrypted_cert_source:
             raise ValueError(
                 "client_cert_source and client_encrypted_cert_source are mutually exclusive"
             )
+        if api_key and credentials_file:
+            raise ValueError("api_key and credentials_file are mutually exclusive")
         self.api_endpoint = api_endpoint
         self.client_cert_source = client_cert_source
         self.client_encrypted_cert_source = client_encrypted_cert_source
         self.quota_project_id = quota_project_id
         self.credentials_file = credentials_file
         self.scopes = scopes
+        self.api_key = api_key
+        self.api_audience = api_audience
+        self.universe_domain = universe_domain
 
-    def __repr__(self):
+    def __repr__(self) -> str:
         return "ClientOptions: " + repr(self.__dict__)
 
 
-def from_dict(options):
+def from_dict(options: Mapping[str, object]) -> ClientOptions:
     """Construct a client options object from a mapping object.
 
     Args:
diff --git a/google/api_core/datetime_helpers.py b/google/api_core/datetime_helpers.py
index 78268efc..c3792300 100644
--- a/google/api_core/datetime_helpers.py
+++ b/google/api_core/datetime_helpers.py
@@ -42,7 +42,7 @@
 
 def utcnow():
     """A :meth:`datetime.datetime.utcnow()` alias to allow mocking in tests."""
-    return datetime.datetime.utcnow()
+    return datetime.datetime.now(tz=datetime.timezone.utc).replace(tzinfo=None)
 
 
 def to_milliseconds(value):
@@ -151,7 +151,7 @@ def from_rfc3339(value):
         micros = 0
     else:
         scale = 9 - len(fraction)
-        nanos = int(fraction) * (10 ** scale)
+        nanos = int(fraction) * (10**scale)
         micros = nanos // 1000
 
     return bare_seconds.replace(microsecond=micros, tzinfo=datetime.timezone.utc)
@@ -170,7 +170,7 @@ def to_rfc3339(value, ignore_zone=True):
             datetime object is ignored and the datetime is treated as UTC.
 
     Returns:
-        str: The RFC3339 formated string representing the datetime.
+        str: The RFC3339 formatted string representing the datetime.
     """
     if not ignore_zone and value.tzinfo is not None:
         # Convert to UTC and remove the time zone info.
@@ -245,7 +245,7 @@ def from_rfc3339(cls, stamp):
             nanos = 0
         else:
             scale = 9 - len(fraction)
-            nanos = int(fraction) * (10 ** scale)
+            nanos = int(fraction) * (10**scale)
         return cls(
             bare.year,
             bare.month,
diff --git a/google/api_core/exceptions.py b/google/api_core/exceptions.py
index 13be917e..e3eb696c 100644
--- a/google/api_core/exceptions.py
+++ b/google/api_core/exceptions.py
@@ -22,17 +22,35 @@
 from __future__ import unicode_literals
 
 import http.client
+from typing import Optional, Dict
+from typing import Union
+import warnings
+
+from google.rpc import error_details_pb2
+
+
+def _warn_could_not_import_grpcio_status():
+    warnings.warn(
+        "Please install grpcio-status to obtain helpful grpc error messages.",
+        ImportWarning,
+    )  # pragma: NO COVER
+
 
 try:
     import grpc
 
+    try:
+        from grpc_status import rpc_status
+    except ImportError:  # pragma: NO COVER
+        _warn_could_not_import_grpcio_status()
+        rpc_status = None
 except ImportError:  # pragma: NO COVER
     grpc = None
 
 # Lookup tables for mapping exceptions from HTTP and gRPC transports.
 # Populated by _GoogleAPICallErrorMeta
-_HTTP_CODE_TO_EXCEPTION = {}
-_GRPC_CODE_TO_EXCEPTION = {}
+_HTTP_CODE_TO_EXCEPTION: Dict[int, Exception] = {}
+_GRPC_CODE_TO_EXCEPTION: Dict[int, Exception] = {}
 
 # Additional lookup table to map integer status codes to grpc status code
 # grpc does not currently support initializing enums from ints
@@ -60,7 +78,7 @@ class RetryError(GoogleAPIError):
 
     Args:
         message (str): The exception message.
-        cause (Exception): The last exception raised when retring the
+        cause (Exception): The last exception raised when retrying the
             function.
     """
 
@@ -96,11 +114,14 @@ class GoogleAPICallError(GoogleAPIError, metaclass=_GoogleAPICallErrorMeta):
     Args:
         message (str): The exception message.
         errors (Sequence[Any]): An optional list of error details.
+        details (Sequence[Any]): An optional list of objects defined in google.rpc.error_details.
         response (Union[requests.Request, grpc.Call]): The response or
             gRPC call metadata.
+        error_info (Union[error_details_pb2.ErrorInfo, None]): An optional object containing error info
+            (google.rpc.error_details.ErrorInfo).
     """
 
-    code = None
+    code: Union[int, None] = None
     """Optional[int]: The HTTP status code associated with this error.
 
     This may be ``None`` if the exception does not have a direct mapping
@@ -116,15 +137,67 @@ class GoogleAPICallError(GoogleAPIError, metaclass=_GoogleAPICallErrorMeta):
     This may be ``None`` if the exception does not match up to a gRPC error.
     """
 
-    def __init__(self, message, errors=(), response=None):
+    def __init__(self, message, errors=(), details=(), response=None, error_info=None):
         super(GoogleAPICallError, self).__init__(message)
         self.message = message
         """str: The exception message."""
         self._errors = errors
+        self._details = details
         self._response = response
+        self._error_info = error_info
 
     def __str__(self):
-        return "{} {}".format(self.code, self.message)
+        error_msg = "{} {}".format(self.code, self.message)
+        if self.details:
+            error_msg = "{} {}".format(error_msg, self.details)
+        # Note: This else condition can be removed once proposal A from
+        # b/284179390 is implemented.
+        else:
+            if self.errors:
+                errors = [
+                    f"{error.code}: {error.message}"
+                    for error in self.errors
+                    if hasattr(error, "code") and hasattr(error, "message")
+                ]
+                if errors:
+                    error_msg = "{} {}".format(error_msg, "\n".join(errors))
+        return error_msg
+
+    @property
+    def reason(self):
+        """The reason of the error.
+
+        Reference:
+            https://github.com/googleapis/googleapis/blob/master/google/rpc/error_details.proto#L112
+
+        Returns:
+            Union[str, None]: An optional string containing reason of the error.
+        """
+        return self._error_info.reason if self._error_info else None
+
+    @property
+    def domain(self):
+        """The logical grouping to which the "reason" belongs.
+
+        Reference:
+            https://github.com/googleapis/googleapis/blob/master/google/rpc/error_details.proto#L112
+
+        Returns:
+            Union[str, None]: An optional string containing a logical grouping to which the "reason" belongs.
+        """
+        return self._error_info.domain if self._error_info else None
+
+    @property
+    def metadata(self):
+        """Additional structured details about this error.
+
+        Reference:
+            https://github.com/googleapis/googleapis/blob/master/google/rpc/error_details.proto#L112
+
+        Returns:
+            Union[Dict[str, str], None]: An optional object containing structured details about the error.
+        """
+        return self._error_info.metadata if self._error_info else None
 
     @property
     def errors(self):
@@ -135,6 +208,19 @@ def errors(self):
         """
         return list(self._errors)
 
+    @property
+    def details(self):
+        """Information contained in google.rpc.status.details.
+
+        Reference:
+            https://github.com/googleapis/googleapis/blob/master/google/rpc/status.proto
+            https://github.com/googleapis/googleapis/blob/master/google/rpc/error_details.proto
+
+        Returns:
+            Sequence[Any]: A list of structured objects from error_details.proto
+        """
+        return list(self._details)
+
     @property
     def response(self):
         """Optional[Union[requests.Request, grpc.Call]]: The response or
@@ -293,8 +379,7 @@ class Cancelled(ClientError):
     """Exception mapping a :attr:`grpc.StatusCode.CANCELLED` error."""
 
     # This maps to HTTP status code 499. See
-    # https://github.com/googleapis/googleapis/blob/master/google/rpc\
-    # /code.proto
+    # https://github.com/googleapis/googleapis/blob/master/google/rpc/code.proto
     code = 499
     grpc_status_code = grpc.StatusCode.CANCELLED if grpc is not None else None
 
@@ -357,6 +442,12 @@ class DeadlineExceeded(GatewayTimeout):
     grpc_status_code = grpc.StatusCode.DEADLINE_EXCEEDED if grpc is not None else None
 
 
+class AsyncRestUnsupportedParameterError(NotImplementedError):
+    """Raised when an unsupported parameter is configured against async rest transport."""
+
+    pass
+
+
 def exception_class_for_http_status(status_code):
     """Return the exception class for a specific HTTP status code.
 
@@ -391,6 +482,62 @@ def from_http_status(status_code, message, **kwargs):
     return error
 
 
+def _format_rest_error_message(error, method, url):
+    method = method.upper() if method else None
+    message = "{method} {url}: {error}".format(
+        method=method,
+        url=url,
+        error=error,
+    )
+    return message
+
+
+# NOTE: We're moving away from `from_http_status` because it expects an aiohttp response compared
+# to `format_http_response_error` which expects a more abstract response from google.auth and is
+# compatible with both sync and async response types.
+# TODO(https://github.com/googleapis/python-api-core/issues/691): Add type hint for response.
+def format_http_response_error(
+    response, method: str, url: str, payload: Optional[Dict] = None
+):
+    """Create a :class:`GoogleAPICallError` from a google auth rest response.
+
+    Args:
+        response Union[google.auth.transport.Response, google.auth.aio.transport.Response]: The HTTP response.
+        method Optional(str): The HTTP request method.
+        url Optional(str): The HTTP request url.
+        payload Optional(dict): The HTTP response payload. If not passed in, it is read from response for a response type of google.auth.transport.Response.
+
+    Returns:
+        GoogleAPICallError: An instance of the appropriate subclass of
+            :class:`GoogleAPICallError`, with the message and errors populated
+            from the response.
+    """
+    payload = {} if not payload else payload
+    error_message = payload.get("error", {}).get("message", "unknown error")
+    errors = payload.get("error", {}).get("errors", ())
+    # In JSON, details are already formatted in developer-friendly way.
+    details = payload.get("error", {}).get("details", ())
+    error_info_list = list(
+        filter(
+            lambda detail: detail.get("@type", "")
+            == "type.googleapis.com/google.rpc.ErrorInfo",
+            details,
+        )
+    )
+    error_info = error_info_list[0] if error_info_list else None
+    message = _format_rest_error_message(error_message, method, url)
+
+    exception = from_http_status(
+        response.status_code,
+        message,
+        errors=errors,
+        details=details,
+        response=response,
+        error_info=error_info,
+    )
+    return exception
+
+
 def from_http_response(response):
     """Create a :class:`GoogleAPICallError` from a :class:`requests.Response`.
 
@@ -406,19 +553,10 @@ def from_http_response(response):
         payload = response.json()
     except ValueError:
         payload = {"error": {"message": response.text or "unknown error"}}
-
-    error_message = payload.get("error", {}).get("message", "unknown error")
-    errors = payload.get("error", {}).get("errors", ())
-
-    message = "{method} {url}: {error}".format(
-        method=response.request.method, url=response.request.url, error=error_message
+    return format_http_response_error(
+        response, response.request.method, response.request.url, payload
     )
 
-    exception = from_http_status(
-        response.status_code, message, errors=errors, response=response
-    )
-    return exception
-
 
 def exception_class_for_grpc_status(status_code):
     """Return the exception class for a specific :class:`grpc.StatusCode`.
@@ -462,6 +600,48 @@ def _is_informative_grpc_error(rpc_exc):
     return hasattr(rpc_exc, "code") and hasattr(rpc_exc, "details")
 
 
+def _parse_grpc_error_details(rpc_exc):
+    if not rpc_status:  # pragma: NO COVER
+        _warn_could_not_import_grpcio_status()
+        return [], None
+    try:
+        status = rpc_status.from_call(rpc_exc)
+    except NotImplementedError:  # workaround
+        return [], None
+
+    if not status:
+        return [], None
+
+    possible_errors = [
+        error_details_pb2.BadRequest,
+        error_details_pb2.PreconditionFailure,
+        error_details_pb2.QuotaFailure,
+        error_details_pb2.ErrorInfo,
+        error_details_pb2.RetryInfo,
+        error_details_pb2.ResourceInfo,
+        error_details_pb2.RequestInfo,
+        error_details_pb2.DebugInfo,
+        error_details_pb2.Help,
+        error_details_pb2.LocalizedMessage,
+    ]
+    error_info = None
+    error_details = []
+    for detail in status.details:
+        matched_detail_cls = list(
+            filter(lambda x: detail.Is(x.DESCRIPTOR), possible_errors)
+        )
+        # If nothing matched, use detail directly.
+        if len(matched_detail_cls) == 0:
+            info = detail
+        else:
+            info = matched_detail_cls[0]()
+            detail.Unpack(info)
+        error_details.append(info)
+        if isinstance(info, error_details_pb2.ErrorInfo):
+            error_info = info
+    return error_details, error_info
+
+
 def from_grpc_error(rpc_exc):
     """Create a :class:`GoogleAPICallError` from a :class:`grpc.RpcError`.
 
@@ -474,9 +654,17 @@ def from_grpc_error(rpc_exc):
     """
     # NOTE(lidiz) All gRPC error shares the parent class grpc.RpcError.
     # However, check for grpc.RpcError breaks backward compatibility.
-    if isinstance(rpc_exc, grpc.Call) or _is_informative_grpc_error(rpc_exc):
+    if (
+        grpc is not None and isinstance(rpc_exc, grpc.Call)
+    ) or _is_informative_grpc_error(rpc_exc):
+        details, err_info = _parse_grpc_error_details(rpc_exc)
         return from_grpc_status(
-            rpc_exc.code(), rpc_exc.details(), errors=(rpc_exc,), response=rpc_exc
+            rpc_exc.code(),
+            rpc_exc.details(),
+            errors=(rpc_exc,),
+            details=details,
+            response=rpc_exc,
+            error_info=err_info,
         )
     else:
         return GoogleAPICallError(str(rpc_exc), errors=(rpc_exc,), response=rpc_exc)
diff --git a/google/api_core/extended_operation.py b/google/api_core/extended_operation.py
new file mode 100644
index 00000000..d474632b
--- /dev/null
+++ b/google/api_core/extended_operation.py
@@ -0,0 +1,225 @@
+# Copyright 2022 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Futures for extended long-running operations returned from Google Cloud APIs.
+
+These futures can be used to synchronously wait for the result of a
+long-running operations using :meth:`ExtendedOperation.result`:
+
+.. code-block:: python
+
+    extended_operation = my_api_client.long_running_method()
+
+    extended_operation.result()
+
+Or asynchronously using callbacks and :meth:`Operation.add_done_callback`:
+
+.. code-block:: python
+
+    extended_operation = my_api_client.long_running_method()
+
+    def my_callback(ex_op):
+        print(f"Operation {ex_op.name} completed")
+
+    extended_operation.add_done_callback(my_callback)
+
+"""
+
+import threading
+
+from google.api_core import exceptions
+from google.api_core.future import polling
+
+
+class ExtendedOperation(polling.PollingFuture):
+    """An ExtendedOperation future for interacting with a Google API Long-Running Operation.
+
+    Args:
+        extended_operation (proto.Message): The initial operation.
+        refresh (Callable[[], type(extended_operation)]): A callable that returns
+            the latest state of the operation.
+        cancel (Callable[[], None]): A callable that tries to cancel the operation.
+        polling Optional(google.api_core.retry.Retry): The configuration used
+            for polling. This can be used to control how often :meth:`done`
+            is polled. If the ``timeout`` argument to :meth:`result` is
+            specified it will override the ``polling.timeout`` property.
+        retry Optional(google.api_core.retry.Retry): DEPRECATED use ``polling``
+            instead. If specified it will override ``polling`` parameter to
+            maintain backward compatibility.
+
+    Note: Most long-running API methods use google.api_core.operation.Operation
+    This class is a wrapper for a subset of methods that use alternative
+    Long-Running Operation (LRO) semantics.
+
+    Note: there is not a concrete type the extended operation must be.
+    It MUST have fields that correspond to the following, POSSIBLY WITH DIFFERENT NAMES:
+    * name: str
+    * status: Union[str, bool, enum.Enum]
+    * error_code: int
+    * error_message: str
+    """
+
+    def __init__(
+        self,
+        extended_operation,
+        refresh,
+        cancel,
+        polling=polling.DEFAULT_POLLING,
+        **kwargs,
+    ):
+        super().__init__(polling=polling, **kwargs)
+        self._extended_operation = extended_operation
+        self._refresh = refresh
+        self._cancel = cancel
+        # Note: the extended operation does not give a good way to indicate cancellation.
+        # We make do with manually tracking cancellation and checking for doneness.
+        self._cancelled = False
+        self._completion_lock = threading.Lock()
+        # Invoke in case the operation came back already complete.
+        self._handle_refreshed_operation()
+
+    # Note: the following four properties MUST be overridden in a subclass
+    # if, and only if, the fields in the corresponding extended operation message
+    # have different names.
+    #
+    # E.g. we have an extended operation class that looks like
+    #
+    # class MyOperation(proto.Message):
+    #     moniker = proto.Field(proto.STRING, number=1)
+    #     status_msg = proto.Field(proto.STRING, number=2)
+    #     optional http_error_code = proto.Field(proto.INT32, number=3)
+    #     optional http_error_msg = proto.Field(proto.STRING, number=4)
+    #
+    # the ExtendedOperation subclass would provide property overrides that map
+    # to these (poorly named) fields.
+    @property
+    def name(self):
+        return self._extended_operation.name
+
+    @property
+    def status(self):
+        return self._extended_operation.status
+
+    @property
+    def error_code(self):
+        return self._extended_operation.error_code
+
+    @property
+    def error_message(self):
+        return self._extended_operation.error_message
+
+    def __getattr__(self, name):
+        return getattr(self._extended_operation, name)
+
+    def done(self, retry=None):
+        self._refresh_and_update(retry)
+        return self._extended_operation.done
+
+    def cancel(self):
+        if self.done():
+            return False
+
+        self._cancel()
+        self._cancelled = True
+        return True
+
+    def cancelled(self):
+        # TODO(dovs): there is not currently a good way to determine whether the
+        # operation has been cancelled.
+        # The best we can do is manually keep track of cancellation
+        # and check for doneness.
+        if not self._cancelled:
+            return False
+
+        self._refresh_and_update()
+        return self._extended_operation.done
+
+    def _refresh_and_update(self, retry=None):
+        if not self._extended_operation.done:
+            self._extended_operation = (
+                self._refresh(retry=retry) if retry else self._refresh()
+            )
+            self._handle_refreshed_operation()
+
+    def _handle_refreshed_operation(self):
+        with self._completion_lock:
+            if not self._extended_operation.done:
+                return
+
+            if self.error_code and self.error_message:
+                # Note: `errors` can be removed once proposal A from
+                # b/284179390 is implemented.
+                errors = []
+                if hasattr(self, "error") and hasattr(self.error, "errors"):
+                    errors = self.error.errors
+                exception = exceptions.from_http_status(
+                    status_code=self.error_code,
+                    message=self.error_message,
+                    response=self._extended_operation,
+                    errors=errors,
+                )
+                self.set_exception(exception)
+            elif self.error_code or self.error_message:
+                exception = exceptions.GoogleAPICallError(
+                    f"Unexpected error {self.error_code}: {self.error_message}"
+                )
+                self.set_exception(exception)
+            else:
+                # Extended operations have no payload.
+                self.set_result(None)
+
+    @classmethod
+    def make(cls, refresh, cancel, extended_operation, **kwargs):
+        """
+        Return an instantiated ExtendedOperation (or child) that wraps
+        * a refresh callable
+        * a cancel callable (can be a no-op)
+        * an initial result
+
+        .. note::
+            It is the caller's responsibility to set up refresh and cancel
+            with their correct request argument.
+            The reason for this is that the services that use Extended Operations
+            have rpcs that look something like the following:
+
+            // service.proto
+            service MyLongService {
+                rpc StartLongTask(StartLongTaskRequest) returns (ExtendedOperation) {
+                    option (google.cloud.operation_service) = "CustomOperationService";
+                }
+            }
+
+            service CustomOperationService {
+                rpc Get(GetOperationRequest) returns (ExtendedOperation) {
+                    option (google.cloud.operation_polling_method) = true;
+                }
+            }
+
+            Any info needed for the poll, e.g. a name, path params, etc.
+            is held in the request, which the initial client method is in a much
+            better position to make made because the caller made the initial request.
+
+            TL;DR: the caller sets up closures for refresh and cancel that carry
+            the properly configured requests.
+
+        Args:
+            refresh (Callable[Optional[Retry]][type(extended_operation)]): A callable that
+                returns the latest state of the operation.
+            cancel (Callable[][Any]): A callable that tries to cancel the operation
+                on a best effort basis.
+            extended_operation (Any): The initial response of the long running method.
+                See the docstring for ExtendedOperation.__init__ for requirements on
+                the type and fields of extended_operation
+        """
+        return cls(extended_operation, refresh, cancel, **kwargs)
diff --git a/google/api_core/future/async_future.py b/google/api_core/future/async_future.py
index 0343fbe2..325ee9cd 100644
--- a/google/api_core/future/async_future.py
+++ b/google/api_core/future/async_future.py
@@ -43,8 +43,10 @@ class AsyncFuture(base.Future):
     The :meth:`done` method should be implemented by subclasses. The polling
     behavior will repeatedly call ``done`` until it returns True.
 
-    .. note: Privacy here is intended to prevent the final class from
-      overexposing, not to prevent subclasses from accessing methods.
+    .. note::
+
+        Privacy here is intended to prevent the final class from
+        overexposing, not to prevent subclasses from accessing methods.
 
     Args:
         retry (google.api_core.retry.Retry): The retry configuration used
@@ -93,7 +95,7 @@ async def _blocking_poll(self, timeout=None):
         if self._future.done():
             return
 
-        retry_ = self._retry.with_deadline(timeout)
+        retry_ = self._retry.with_timeout(timeout)
 
         try:
             await retry_(self._done_or_raise)()
diff --git a/google/api_core/future/polling.py b/google/api_core/future/polling.py
index 2f80efb5..f1e2a188 100644
--- a/google/api_core/future/polling.py
+++ b/google/api_core/future/polling.py
@@ -18,7 +18,7 @@
 import concurrent.futures
 
 from google.api_core import exceptions
-from google.api_core import retry
+from google.api_core import retry as retries
 from google.api_core.future import _helpers
 from google.api_core.future import base
 
@@ -29,14 +29,37 @@ class _OperationNotComplete(Exception):
     pass
 
 
-RETRY_PREDICATE = retry.if_exception_type(
+# DEPRECATED as it conflates RPC retry and polling concepts into one.
+# Use POLLING_PREDICATE instead to configure polling.
+RETRY_PREDICATE = retries.if_exception_type(
     _OperationNotComplete,
     exceptions.TooManyRequests,
     exceptions.InternalServerError,
     exceptions.BadGateway,
     exceptions.ServiceUnavailable,
 )
-DEFAULT_RETRY = retry.Retry(predicate=RETRY_PREDICATE)
+
+# DEPRECATED: use DEFAULT_POLLING to configure LRO polling logic. Construct
+# Retry object using its default values as a baseline for any custom retry logic
+# (not to be confused with polling logic).
+DEFAULT_RETRY = retries.Retry(predicate=RETRY_PREDICATE)
+
+# POLLING_PREDICATE is supposed to poll only on _OperationNotComplete.
+# Any RPC-specific errors (like ServiceUnavailable) will be handled
+# by retry logic (not to be confused with polling logic) which is triggered for
+# every polling RPC independently of polling logic but within its context.
+POLLING_PREDICATE = retries.if_exception_type(
+    _OperationNotComplete,
+)
+
+# Default polling configuration
+DEFAULT_POLLING = retries.Retry(
+    predicate=POLLING_PREDICATE,
+    initial=1.0,  # seconds
+    maximum=20.0,  # seconds
+    multiplier=1.5,
+    timeout=900,  # seconds
+)
 
 
 class PollingFuture(base.Future):
@@ -45,19 +68,29 @@ class PollingFuture(base.Future):
     The :meth:`done` method should be implemented by subclasses. The polling
     behavior will repeatedly call ``done`` until it returns True.
 
-    .. note: Privacy here is intended to prevent the final class from
-      overexposing, not to prevent subclasses from accessing methods.
+    The actual polling logic is encapsulated in :meth:`result` method. See
+    documentation for that method for details on how polling works.
+
+    .. note::
+
+        Privacy here is intended to prevent the final class from
+        overexposing, not to prevent subclasses from accessing methods.
 
     Args:
-        retry (google.api_core.retry.Retry): The retry configuration used
-            when polling. This can be used to control how often :meth:`done`
-            is polled. Regardless of the retry's ``deadline``, it will be
-            overridden by the ``timeout`` argument to :meth:`result`.
+        polling (google.api_core.retry.Retry): The configuration used for polling.
+            This parameter controls how often :meth:`done` is polled. If the
+            ``timeout`` argument is specified in :meth:`result` method it will
+            override the ``polling.timeout`` property.
+        retry (google.api_core.retry.Retry): DEPRECATED use ``polling`` instead.
+            If set, it will override ``polling`` parameter for backward
+            compatibility.
     """
 
-    def __init__(self, retry=DEFAULT_RETRY):
+    _DEFAULT_VALUE = object()
+
+    def __init__(self, polling=DEFAULT_POLLING, **kwargs):
         super(PollingFuture, self).__init__()
-        self._retry = retry
+        self._polling = kwargs.get("retry", polling)
         self._result = None
         self._exception = None
         self._result_set = False
@@ -67,11 +100,13 @@ def __init__(self, retry=DEFAULT_RETRY):
         self._done_callbacks = []
 
     @abc.abstractmethod
-    def done(self, retry=DEFAULT_RETRY):
+    def done(self, retry=None):
         """Checks to see if the operation is complete.
 
         Args:
-            retry (google.api_core.retry.Retry): (Optional) How to retry the RPC.
+            retry (google.api_core.retry.Retry): (Optional) How to retry the
+                polling RPC (to not be confused with polling configuration. See
+                the documentation for :meth:`result` for details).
 
         Returns:
             bool: True if the operation is complete, False otherwise.
@@ -79,45 +114,136 @@ def done(self, retry=DEFAULT_RETRY):
         # pylint: disable=redundant-returns-doc, missing-raises-doc
         raise NotImplementedError()
 
-    def _done_or_raise(self, retry=DEFAULT_RETRY):
+    def _done_or_raise(self, retry=None):
         """Check if the future is done and raise if it's not."""
-        kwargs = {} if retry is DEFAULT_RETRY else {"retry": retry}
-
-        if not self.done(**kwargs):
+        if not self.done(retry=retry):
             raise _OperationNotComplete()
 
     def running(self):
         """True if the operation is currently running."""
         return not self.done()
 
-    def _blocking_poll(self, timeout=None, retry=DEFAULT_RETRY):
-        """Poll and wait for the Future to be resolved.
+    def _blocking_poll(self, timeout=_DEFAULT_VALUE, retry=None, polling=None):
+        """Poll and wait for the Future to be resolved."""
 
-        Args:
-            timeout (int):
-                How long (in seconds) to wait for the operation to complete.
-                If None, wait indefinitely.
-        """
         if self._result_set:
             return
 
-        retry_ = self._retry.with_deadline(timeout)
+        polling = polling or self._polling
+        if timeout is not PollingFuture._DEFAULT_VALUE:
+            polling = polling.with_timeout(timeout)
 
         try:
-            kwargs = {} if retry is DEFAULT_RETRY else {"retry": retry}
-            retry_(self._done_or_raise)(**kwargs)
+            polling(self._done_or_raise)(retry=retry)
         except exceptions.RetryError:
             raise concurrent.futures.TimeoutError(
-                "Operation did not complete within the designated " "timeout."
+                f"Operation did not complete within the designated timeout of "
+                f"{polling.timeout} seconds."
             )
 
-    def result(self, timeout=None, retry=DEFAULT_RETRY):
-        """Get the result of the operation, blocking if necessary.
+    def result(self, timeout=_DEFAULT_VALUE, retry=None, polling=None):
+        """Get the result of the operation.
+
+        This method will poll for operation status periodically, blocking if
+        necessary. If you just want to make sure that this method does not block
+        for more than X seconds and you do not care about the nitty-gritty of
+        how this method operates, just call it with ``result(timeout=X)``. The
+        other parameters are for advanced use only.
+
+        Every call to this method is controlled by the following three
+        parameters, each of which has a specific, distinct role, even though all three
+        may look very similar: ``timeout``, ``retry`` and ``polling``. In most
+        cases users do not need to specify any custom values for any of these
+        parameters and may simply rely on default ones instead.
+
+        If you choose to specify custom parameters, please make sure you've
+        read the documentation below carefully.
+
+        First, please check :class:`google.api_core.retry.Retry`
+        class documentation for the proper definition of timeout and deadline
+        terms and for the definition the three different types of timeouts.
+        This class operates in terms of Retry Timeout and Polling Timeout. It
+        does not let customizing RPC timeout and the user is expected to rely on
+        default behavior for it.
+
+        The roles of each argument of this method are as follows:
+
+        ``timeout`` (int): (Optional) The Polling Timeout as defined in
+        :class:`google.api_core.retry.Retry`. If the operation does not complete
+        within this timeout an exception will be thrown. This parameter affects
+        neither Retry Timeout nor RPC Timeout.
+
+        ``retry`` (google.api_core.retry.Retry): (Optional) How to retry the
+        polling RPC. The ``retry.timeout`` property of this parameter is the
+        Retry Timeout as defined in :class:`google.api_core.retry.Retry`.
+        This parameter defines ONLY how the polling RPC call is retried
+        (i.e. what to do if the RPC we used for polling returned an error). It
+        does NOT define how the polling is done (i.e. how frequently and for
+        how long to call the polling RPC); use the ``polling`` parameter for that.
+        If a polling RPC throws and error and retrying it fails, the whole
+        future fails with the corresponding exception. If you want to tune which
+        server response error codes are not fatal for operation polling, use this
+        parameter to control that (``retry.predicate`` in particular).
+
+        ``polling`` (google.api_core.retry.Retry): (Optional) How often and
+        for how long to call the polling RPC periodically (i.e. what to do if
+        a polling rpc returned successfully but its returned result indicates
+        that the long running operation is not completed yet, so we need to
+        check it again at some point in future). This parameter does NOT define
+        how to retry each individual polling RPC in case of an error; use the
+        ``retry`` parameter for that. The ``polling.timeout`` of this parameter
+        is Polling Timeout as defined in as defined in
+        :class:`google.api_core.retry.Retry`.
+
+        For each of the arguments, there are also default values in place, which
+        will be used if a user does not specify their own. The default values
+        for the three parameters are not to be confused with the default values
+        for the corresponding arguments in this method (those serve as "not set"
+        markers for the resolution logic).
+
+        If ``timeout`` is provided (i.e.``timeout is not _DEFAULT VALUE``; note
+        the ``None`` value means "infinite timeout"), it will be used to control
+        the actual Polling Timeout. Otherwise, the ``polling.timeout`` value
+        will be used instead (see below for how the ``polling`` config itself
+        gets resolved). In other words, this parameter  effectively overrides
+        the ``polling.timeout`` value if specified. This is so to preserve
+        backward compatibility.
+
+        If ``retry`` is provided (i.e. ``retry is not None``) it will be used to
+        control retry behavior for the polling RPC and the ``retry.timeout``
+        will determine the Retry Timeout. If not provided, the
+        polling RPC will be called with whichever default retry config was
+        specified for the polling RPC at the moment of the construction of the
+        polling RPC's client. For example, if the polling RPC is
+        ``operations_client.get_operation()``, the ``retry`` parameter will be
+        controlling its retry behavior (not polling  behavior) and, if not
+        specified, that specific method (``operations_client.get_operation()``)
+        will be retried according to the default retry config provided during
+        creation of ``operations_client`` client instead. This argument exists
+        mainly for backward compatibility; users are very unlikely to ever need
+        to set this parameter explicitly.
+
+        If ``polling`` is provided (i.e. ``polling is not None``), it will be used
+        to control the overall polling behavior and ``polling.timeout`` will
+        control Polling Timeout unless it is overridden by ``timeout`` parameter
+        as described above. If not provided, the``polling`` parameter specified
+        during construction of this future (the ``polling`` argument in the
+        constructor) will be used instead. Note: since the ``timeout`` argument may
+        override ``polling.timeout`` value, this parameter should be viewed as
+        coupled with the ``timeout`` parameter as described above.
 
         Args:
-            timeout (int):
-                How long (in seconds) to wait for the operation to complete.
-                If None, wait indefinitely.
+            timeout (int): (Optional) How long (in seconds) to wait for the
+                operation to complete. If None, wait indefinitely.
+            retry (google.api_core.retry.Retry): (Optional) How to retry the
+                polling RPC. This defines ONLY how the polling RPC call is
+                retried (i.e. what to do if the RPC we used for polling returned
+                an error). It does  NOT define how the polling is done (i.e. how
+                frequently and for how long to call the polling RPC).
+            polling (google.api_core.retry.Retry): (Optional) How often and
+                for how long to call polling RPC periodically. This parameter
+                does NOT define how to retry each individual polling RPC call
+                (use the ``retry`` parameter for that).
 
         Returns:
             google.protobuf.Message: The Operation's result.
@@ -126,8 +252,8 @@ def result(self, timeout=None, retry=DEFAULT_RETRY):
             google.api_core.GoogleAPICallError: If the operation errors or if
                 the timeout is reached before the operation completes.
         """
-        kwargs = {} if retry is DEFAULT_RETRY else {"retry": retry}
-        self._blocking_poll(timeout=timeout, **kwargs)
+
+        self._blocking_poll(timeout=timeout, retry=retry, polling=polling)
 
         if self._exception is not None:
             # pylint: disable=raising-bad-type
@@ -136,12 +262,18 @@ def result(self, timeout=None, retry=DEFAULT_RETRY):
 
         return self._result
 
-    def exception(self, timeout=None):
+    def exception(self, timeout=_DEFAULT_VALUE):
         """Get the exception from the operation, blocking if necessary.
 
+        See the documentation for the :meth:`result` method for details on how
+        this method operates, as both ``result`` and this method rely on the
+        exact same polling logic. The only difference is that this method does
+        not accept ``retry`` and ``polling`` arguments but relies on the default ones
+        instead.
+
         Args:
             timeout (int): How long to wait for the operation to complete.
-                If None, wait indefinitely.
+            If None, wait indefinitely.
 
         Returns:
             Optional[google.api_core.GoogleAPICallError]: The operation's
diff --git a/google/api_core/gapic_v1/client_info.py b/google/api_core/gapic_v1/client_info.py
index fab0f542..4516f339 100644
--- a/google/api_core/gapic_v1/client_info.py
+++ b/google/api_core/gapic_v1/client_info.py
@@ -36,7 +36,7 @@ class ClientInfo(client_info.ClientInfo):
             ``'3.9.6'``.
         grpc_version (Optional[str]): The gRPC library version.
         api_core_version (str): The google-api-core library version.
-        gapic_version (Optional[str]): The sversion of gapic-generated client
+        gapic_version (Optional[str]): The version of gapic-generated client
             library, if the library was generated by gapic.
         client_library_version (Optional[str]): The version of the client
             library, generally used if the client library was not generated
@@ -45,6 +45,8 @@ class ClientInfo(client_info.ClientInfo):
         user_agent (Optional[str]): Prefix to the user agent header. This is
             used to supply information such as application name or partner tool.
             Recommended format: ``application-or-tool-ID/major.minor.version``.
+        rest_version (Optional[str]): A string with labeled versions of the
+            dependencies used for REST transport.
     """
 
     def to_grpc_metadata(self):
diff --git a/google/api_core/gapic_v1/config.py b/google/api_core/gapic_v1/config.py
index 9c722871..36b50d9f 100644
--- a/google/api_core/gapic_v1/config.py
+++ b/google/api_core/gapic_v1/config.py
@@ -33,6 +33,9 @@
 def _exception_class_for_grpc_status_name(name):
     """Returns the Google API exception class for a gRPC error code name.
 
+    DEPRECATED: use ``exceptions.exception_class_for_grpc_status`` method
+    directly instead.
+
     Args:
         name (str): The name of the gRPC status code, for example,
             ``UNAVAILABLE``.
@@ -47,6 +50,8 @@ def _exception_class_for_grpc_status_name(name):
 def _retry_from_retry_config(retry_params, retry_codes, retry_impl=retry.Retry):
     """Creates a Retry object given a gapic retry configuration.
 
+    DEPRECATED: instantiate retry and timeout classes directly instead.
+
     Args:
         retry_params (dict): The retry parameter values, for example::
 
@@ -81,6 +86,8 @@ def _retry_from_retry_config(retry_params, retry_codes, retry_impl=retry.Retry):
 def _timeout_from_retry_config(retry_params):
     """Creates a ExponentialTimeout object given a gapic retry configuration.
 
+    DEPRECATED: instantiate retry and timeout classes directly instead.
+
     Args:
         retry_params (dict): The retry parameter values, for example::
 
@@ -113,6 +120,8 @@ def parse_method_configs(interface_config, retry_impl=retry.Retry):
     """Creates default retry and timeout objects for each method in a gapic
     interface config.
 
+    DEPRECATED: instantiate retry and timeout classes directly instead.
+
     Args:
         interface_config (Mapping): The interface config section of the full
             gapic library config. For example, If the full configuration has
diff --git a/google/api_core/gapic_v1/method.py b/google/api_core/gapic_v1/method.py
index 79722c07..0f14ea9c 100644
--- a/google/api_core/gapic_v1/method.py
+++ b/google/api_core/gapic_v1/method.py
@@ -15,18 +15,30 @@
 """Helpers for wrapping low-level gRPC methods with common functionality.
 
 This is used by gapic clients to provide common error mapping, retry, timeout,
-pagination, and long-running operations to gRPC methods.
+compression, pagination, and long-running operations to gRPC methods.
 """
 
+import enum
 import functools
 
 from google.api_core import grpc_helpers
-from google.api_core import timeout
 from google.api_core.gapic_v1 import client_info
+from google.api_core.timeout import TimeToDeadlineTimeout
 
 USE_DEFAULT_METADATA = object()
-DEFAULT = object()
-"""Sentinel value indicating that a retry or timeout argument was unspecified,
+
+
+class _MethodDefault(enum.Enum):
+    # Uses enum so that pytype/mypy knows that this is the only possible value.
+    # https://stackoverflow.com/a/60605919/101923
+    #
+    # Literal[_DEFAULT_VALUE] is an alternative, but only added in Python 3.8.
+    # https://docs.python.org/3/library/typing.html#typing.Literal
+    _DEFAULT_VALUE = object()
+
+
+DEFAULT = _MethodDefault._DEFAULT_VALUE
+"""Sentinel value indicating that a retry, timeout, or compression argument was unspecified,
 so the default should be used."""
 
 
@@ -40,55 +52,14 @@ def _apply_decorators(func, decorators):
     ``decorators`` may contain items that are ``None`` or ``False`` which will
     be ignored.
     """
-    decorators = filter(_is_not_none_or_false, reversed(decorators))
+    filtered_decorators = filter(_is_not_none_or_false, reversed(decorators))
 
-    for decorator in decorators:
+    for decorator in filtered_decorators:
         func = decorator(func)
 
     return func
 
 
-def _determine_timeout(default_timeout, specified_timeout, retry):
-    """Determines how timeout should be applied to a wrapped method.
-
-    Args:
-        default_timeout (Optional[Timeout]): The default timeout specified
-            at method creation time.
-        specified_timeout (Optional[Timeout]): The timeout specified at
-            invocation time. If :attr:`DEFAULT`, this will be set to
-            the ``default_timeout``.
-        retry (Optional[Retry]): The retry specified at invocation time.
-
-    Returns:
-        Optional[Timeout]: The timeout to apply to the method or ``None``.
-    """
-    # If timeout is specified as a number instead of a Timeout instance,
-    # convert it to a ConstantTimeout.
-    if isinstance(specified_timeout, (int, float)):
-        specified_timeout = timeout.ConstantTimeout(specified_timeout)
-    if isinstance(default_timeout, (int, float)):
-        default_timeout = timeout.ConstantTimeout(default_timeout)
-
-    if specified_timeout is DEFAULT:
-        specified_timeout = default_timeout
-
-    if specified_timeout is default_timeout:
-        # If timeout is the default and the default timeout is exponential and
-        # a non-default retry is specified, make sure the timeout's deadline
-        # matches the retry's. This handles the case where the user leaves
-        # the timeout default but specifies a lower deadline via the retry.
-        if (
-            retry
-            and retry is not DEFAULT
-            and isinstance(default_timeout, timeout.ExponentialTimeout)
-        ):
-            return default_timeout.with_deadline(retry._deadline)
-        else:
-            return default_timeout
-
-    return specified_timeout
-
-
 class _GapicCallable(object):
     """Callable that applies retry, timeout, and metadata logic.
 
@@ -96,35 +67,51 @@ class _GapicCallable(object):
         target (Callable): The low-level RPC method.
         retry (google.api_core.retry.Retry): The default retry for the
             callable. If ``None``, this callable will not retry by default
-        timeout (google.api_core.timeout.Timeout): The default timeout
-            for the callable. If ``None``, this callable will not specify
-            a timeout argument to the low-level RPC method by default.
+        timeout (google.api_core.timeout.Timeout): The default timeout for the
+            callable (i.e. duration of time within which an RPC must terminate
+            after its start, not to be confused with deadline). If ``None``,
+            this callable will not specify a timeout argument to the low-level
+            RPC method.
+        compression (grpc.Compression): The default compression for the callable.
+            If ``None``, this callable will not specify a compression argument
+            to the low-level RPC method.
         metadata (Sequence[Tuple[str, str]]): Additional metadata that is
             provided to the RPC method on every invocation. This is merged with
             any metadata specified during invocation. If ``None``, no
             additional metadata will be passed to the RPC method.
     """
 
-    def __init__(self, target, retry, timeout, metadata=None):
+    def __init__(
+        self,
+        target,
+        retry,
+        timeout,
+        compression,
+        metadata=None,
+    ):
         self._target = target
         self._retry = retry
         self._timeout = timeout
+        self._compression = compression
         self._metadata = metadata
 
-    def __call__(self, *args, timeout=DEFAULT, retry=DEFAULT, **kwargs):
-        """Invoke the low-level RPC with retry, timeout, and metadata."""
-        timeout = _determine_timeout(
-            self._timeout,
-            timeout,
-            # Use only the invocation-specified retry only for this, as we only
-            # want to adjust the timeout deadline if the *user* specified
-            # a different retry.
-            retry,
-        )
+    def __call__(
+        self, *args, timeout=DEFAULT, retry=DEFAULT, compression=DEFAULT, **kwargs
+    ):
+        """Invoke the low-level RPC with retry, timeout, compression, and metadata."""
 
         if retry is DEFAULT:
             retry = self._retry
 
+        if timeout is DEFAULT:
+            timeout = self._timeout
+
+        if compression is DEFAULT:
+            compression = self._compression
+
+        if isinstance(timeout, (int, float)):
+            timeout = TimeToDeadlineTimeout(timeout=timeout)
+
         # Apply all applicable decorators.
         wrapped_func = _apply_decorators(self._target, [retry, timeout])
 
@@ -138,6 +125,8 @@ def __call__(self, *args, timeout=DEFAULT, retry=DEFAULT, **kwargs):
             metadata = list(metadata)
             metadata.extend(self._metadata)
             kwargs["metadata"] = metadata
+        if self._compression is not None:
+            kwargs["compression"] = compression
 
         return wrapped_func(*args, **kwargs)
 
@@ -146,12 +135,15 @@ def wrap_method(
     func,
     default_retry=None,
     default_timeout=None,
+    default_compression=None,
     client_info=client_info.DEFAULT_CLIENT_INFO,
+    *,
+    with_call=False,
 ):
     """Wrap an RPC method with common behavior.
 
-    This applies common error wrapping, retry, and timeout behavior a function.
-    The wrapped function will take optional ``retry`` and ``timeout``
+    This applies common error wrapping, retry, timeout, and compression behavior to a function.
+    The wrapped function will take optional ``retry``, ``timeout``, and ``compression``
     arguments.
 
     For example::
@@ -159,6 +151,7 @@ def wrap_method(
         import google.api_core.gapic_v1.method
         from google.api_core import retry
         from google.api_core import timeout
+        from grpc import Compression
 
         # The original RPC method.
         def get_topic(name, timeout=None):
@@ -167,6 +160,7 @@ def get_topic(name, timeout=None):
 
         default_retry = retry.Retry(deadline=60)
         default_timeout = timeout.Timeout(deadline=60)
+        default_compression = Compression.NoCompression
         wrapped_get_topic = google.api_core.gapic_v1.method.wrap_method(
             get_topic, default_retry)
 
@@ -215,20 +209,34 @@ def get_topic(name, timeout=None):
         default_timeout (Optional[google.api_core.Timeout]): The default
             timeout strategy. Can also be specified as an int or float. If
             ``None``, the method will not have timeout specified by default.
+        default_compression (Optional[grpc.Compression]): The default
+            grpc.Compression. If ``None``, the method will not have
+            compression specified by default.
         client_info
             (Optional[google.api_core.gapic_v1.client_info.ClientInfo]):
                 Client information used to create a user-agent string that's
                 passed as gRPC metadata to the method. If unspecified, then
                 a sane default will be used. If ``None``, then no user agent
                 metadata will be provided to the RPC method.
+        with_call (bool): If True, wrapped grpc.UnaryUnaryMulticallables will
+            return a tuple of (response, grpc.Call) instead of just the response.
+            This is useful for extracting trailing metadata from unary calls.
+            Defaults to False.
 
     Returns:
-        Callable: A new callable that takes optional ``retry`` and ``timeout``
-            arguments and applies the common error mapping, retry, timeout,
+        Callable: A new callable that takes optional ``retry``, ``timeout``,
+            and ``compression``
+            arguments and applies the common error mapping, retry, timeout, compression,
             and metadata behavior to the low-level RPC method.
     """
+    if with_call:
+        try:
+            func = func.with_call
+        except AttributeError as exc:
+            raise ValueError(
+                "with_call=True is only supported for unary calls."
+            ) from exc
     func = grpc_helpers.wrap_errors(func)
-
     if client_info is not None:
         user_agent_metadata = [client_info.to_grpc_metadata()]
     else:
@@ -236,6 +244,10 @@ def get_topic(name, timeout=None):
 
     return functools.wraps(func)(
         _GapicCallable(
-            func, default_retry, default_timeout, metadata=user_agent_metadata
+            func,
+            default_retry,
+            default_timeout,
+            default_compression,
+            metadata=user_agent_metadata,
         )
     )
diff --git a/google/api_core/gapic_v1/method_async.py b/google/api_core/gapic_v1/method_async.py
index 84c99aa2..c0f38c0e 100644
--- a/google/api_core/gapic_v1/method_async.py
+++ b/google/api_core/gapic_v1/method_async.py
@@ -14,7 +14,7 @@
 """AsyncIO helpers for wrapping gRPC methods with common functionality.
 
 This is used by gapic clients to provide common error mapping, retry, timeout,
-pagination, and long-running operations to gRPC methods.
+compression, pagination, and long-running operations to gRPC methods.
 """
 
 import functools
@@ -25,24 +25,35 @@
 from google.api_core.gapic_v1.method import DEFAULT  # noqa: F401
 from google.api_core.gapic_v1.method import USE_DEFAULT_METADATA  # noqa: F401
 
+_DEFAULT_ASYNC_TRANSPORT_KIND = "grpc_asyncio"
+
 
 def wrap_method(
     func,
     default_retry=None,
     default_timeout=None,
+    default_compression=None,
     client_info=client_info.DEFAULT_CLIENT_INFO,
+    kind=_DEFAULT_ASYNC_TRANSPORT_KIND,
 ):
     """Wrap an async RPC method with common behavior.
 
     Returns:
-        Callable: A new callable that takes optional ``retry`` and ``timeout``
-            arguments and applies the common error mapping, retry, timeout,
-            and metadata behavior to the low-level RPC method.
+        Callable: A new callable that takes optional ``retry``, ``timeout``,
+            and ``compression`` arguments and applies the common error mapping,
+            retry, timeout, metadata, and compression behavior to the low-level RPC method.
     """
-    func = grpc_helpers_async.wrap_errors(func)
+    if kind == _DEFAULT_ASYNC_TRANSPORT_KIND:
+        func = grpc_helpers_async.wrap_errors(func)
 
     metadata = [client_info.to_grpc_metadata()] if client_info is not None else None
 
     return functools.wraps(func)(
-        _GapicCallable(func, default_retry, default_timeout, metadata=metadata)
+        _GapicCallable(
+            func,
+            default_retry,
+            default_timeout,
+            default_compression,
+            metadata=metadata,
+        )
     )
diff --git a/google/api_core/gapic_v1/routing_header.py b/google/api_core/gapic_v1/routing_header.py
index a7bcb5a8..c0c6f648 100644
--- a/google/api_core/gapic_v1/routing_header.py
+++ b/google/api_core/gapic_v1/routing_header.py
@@ -20,38 +20,68 @@
 Generally, these headers are specified as gRPC metadata.
 """
 
+import functools
+from enum import Enum
 from urllib.parse import urlencode
 
 ROUTING_METADATA_KEY = "x-goog-request-params"
+# This is the value for the `maxsize` argument of @functools.lru_cache
+# https://docs.python.org/3/library/functools.html#functools.lru_cache
+# This represents the number of recent function calls to store.
+ROUTING_PARAM_CACHE_SIZE = 32
 
 
-def to_routing_header(params):
+def to_routing_header(params, qualified_enums=True):
     """Returns a routing header string for the given request parameters.
 
     Args:
-        params (Mapping[str, Any]): A dictionary containing the request
+        params (Mapping[str, str | bytes | Enum]): A dictionary containing the request
             parameters used for routing.
+        qualified_enums (bool): Whether to represent enum values
+            as their type-qualified symbol names instead of as their
+            unqualified symbol names.
 
     Returns:
         str: The routing header string.
     """
-    return urlencode(
-        params,
-        # Per Google API policy (go/api-url-encoding), / is not encoded.
-        safe="/",
-    )
+    tuples = params.items() if isinstance(params, dict) else params
+    if not qualified_enums:
+        tuples = [(x[0], x[1].name) if isinstance(x[1], Enum) else x for x in tuples]
+    return "&".join([_urlencode_param(*t) for t in tuples])
 
 
-def to_grpc_metadata(params):
+def to_grpc_metadata(params, qualified_enums=True):
     """Returns the gRPC metadata containing the routing headers for the given
     request parameters.
 
     Args:
-        params (Mapping[str, Any]): A dictionary containing the request
+        params (Mapping[str, str | bytes | Enum]): A dictionary containing the request
             parameters used for routing.
+        qualified_enums (bool): Whether to represent enum values
+            as their type-qualified symbol names instead of as their
+            unqualified symbol names.
 
     Returns:
         Tuple(str, str): The gRPC metadata containing the routing header key
             and value.
     """
-    return (ROUTING_METADATA_KEY, to_routing_header(params))
+    return (ROUTING_METADATA_KEY, to_routing_header(params, qualified_enums))
+
+
+# use caching to avoid repeated computation
+@functools.lru_cache(maxsize=ROUTING_PARAM_CACHE_SIZE)
+def _urlencode_param(key, value):
+    """Cacheable wrapper over urlencode
+
+    Args:
+        key (str): The key of the parameter to encode.
+        value (str | bytes | Enum): The value of the parameter to encode.
+
+    Returns:
+        str: The encoded parameter.
+    """
+    return urlencode(
+        {key: value},
+        # Per Google API policy (go/api-url-encoding), / is not encoded.
+        safe="/",
+    )
diff --git a/google/api_core/general_helpers.py b/google/api_core/general_helpers.py
index fba78026..a6af45b7 100644
--- a/google/api_core/general_helpers.py
+++ b/google/api_core/general_helpers.py
@@ -12,5 +12,5 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# This import for backward compatibiltiy only.
+# This import for backward compatibility only.
 from functools import wraps  # noqa: F401 pragma: NO COVER
diff --git a/google/api_core/grpc_helpers.py b/google/api_core/grpc_helpers.py
index 594df987..07963024 100644
--- a/google/api_core/grpc_helpers.py
+++ b/google/api_core/grpc_helpers.py
@@ -13,38 +13,48 @@
 # limitations under the License.
 
 """Helpers for :mod:`grpc`."""
+from typing import Generic, Iterator, Optional, TypeVar
 
 import collections
 import functools
+import warnings
 
 import grpc
-import pkg_resources
 
 from google.api_core import exceptions
 import google.auth
 import google.auth.credentials
 import google.auth.transport.grpc
 import google.auth.transport.requests
+import google.protobuf
 
-try:
-    import grpc_gcp
+PROTOBUF_VERSION = google.protobuf.__version__
 
-    HAS_GRPC_GCP = True
-except ImportError:
+# The grpcio-gcp package only has support for protobuf < 4
+if PROTOBUF_VERSION[0:2] == "3.":  # pragma: NO COVER
+    try:
+        import grpc_gcp
+
+        warnings.warn(
+            """Support for grpcio-gcp is deprecated. This feature will be
+            removed from `google-api-core` after January 1, 2024. If you need to
+            continue to use this feature, please pin to a specific version of
+            `google-api-core`.""",
+            DeprecationWarning,
+        )
+        HAS_GRPC_GCP = True
+    except ImportError:
+        HAS_GRPC_GCP = False
+else:
     HAS_GRPC_GCP = False
 
-try:
-    # google.auth.__version__ was added in 1.26.0
-    _GOOGLE_AUTH_VERSION = google.auth.__version__
-except AttributeError:
-    try:  # try pkg_resources if it is available
-        _GOOGLE_AUTH_VERSION = pkg_resources.get_distribution("google-auth").version
-    except pkg_resources.DistributionNotFound:  # pragma: NO COVER
-        _GOOGLE_AUTH_VERSION = None
 
 # The list of gRPC Callable interfaces that return iterators.
 _STREAM_WRAP_CLASSES = (grpc.UnaryStreamMultiCallable, grpc.StreamStreamMultiCallable)
 
+# denotes the proto response type for grpc calls
+P = TypeVar("P")
+
 
 def _patch_callable_name(callable_):
     """Fix-up gRPC callable attributes.
@@ -70,7 +80,7 @@ def error_remapped_callable(*args, **kwargs):
     return error_remapped_callable
 
 
-class _StreamingResponseIterator(grpc.Call):
+class _StreamingResponseIterator(Generic[P], grpc.Call):
     def __init__(self, wrapped, prefetch_first_result=True):
         self._wrapped = wrapped
 
@@ -88,11 +98,11 @@ def __init__(self, wrapped, prefetch_first_result=True):
             # ignore stop iteration at this time. This should be handled outside of retry.
             pass
 
-    def __iter__(self):
+    def __iter__(self) -> Iterator[P]:
         """This iterator is also an iterable that returns itself."""
         return self
 
-    def __next__(self):
+    def __next__(self) -> P:
         """Get the next response from the stream.
 
         Returns:
@@ -135,6 +145,10 @@ def trailing_metadata(self):
         return self._wrapped.trailing_metadata()
 
 
+# public type alias denoting the return type of streaming gapic calls
+GrpcStream = _StreamingResponseIterator[P]
+
+
 def _wrap_stream_errors(callable_):
     """Wrap errors for Unary-Stream and Stream-Stream gRPC callables.
 
@@ -202,6 +216,18 @@ def _create_composite_credentials(
         credentials_file (str): A file with credentials that can be loaded with
             :func:`google.auth.load_credentials_from_file`. This argument is
             mutually exclusive with credentials.
+
+            .. warning::
+                Important: If you accept a credential configuration (credential JSON/File/Stream)
+                from an external source for authentication to Google Cloud Platform, you must
+                validate it before providing it to any Google API or client library. Providing an
+                unvalidated credential configuration to Google APIs or libraries can compromise
+                the security of your systems and data. For more information, refer to
+                `Validate credential configurations from external sources`_.
+
+            .. _Validate credential configurations from external sources:
+
+            https://cloud.google.com/docs/authentication/external/externally-sourced-credentials
         default_scopes (Sequence[str]): A optional list of scopes needed for this
             service. These are only used when credentials are not specified and
             are passed to :func:`google.auth.default`.
@@ -246,17 +272,32 @@ def _create_composite_credentials(
 
     # Create the metadata plugin for inserting the authorization header.
     metadata_plugin = google.auth.transport.grpc.AuthMetadataPlugin(
-        credentials, request, default_host=default_host,
+        credentials,
+        request,
+        default_host=default_host,
     )
 
     # Create a set of grpc.CallCredentials using the metadata plugin.
     google_auth_credentials = grpc.metadata_call_credentials(metadata_plugin)
 
-    if ssl_credentials is None:
-        ssl_credentials = grpc.ssl_channel_credentials()
-
-    # Combine the ssl credentials and the authorization credentials.
-    return grpc.composite_channel_credentials(ssl_credentials, google_auth_credentials)
+    # if `ssl_credentials` is set, use `grpc.composite_channel_credentials` instead of
+    # `grpc.compute_engine_channel_credentials` as the former supports passing
+    # `ssl_credentials` via `channel_credentials` which is needed for mTLS.
+    if ssl_credentials:
+        # Combine the ssl credentials and the authorization credentials.
+        # See https://grpc.github.io/grpc/python/grpc.html#grpc.composite_channel_credentials
+        return grpc.composite_channel_credentials(
+            ssl_credentials, google_auth_credentials
+        )
+    else:
+        # Use grpc.compute_engine_channel_credentials in order to support Direct Path.
+        # See https://grpc.github.io/grpc/python/grpc.html#grpc.compute_engine_channel_credentials
+        # TODO(https://github.com/googleapis/python-api-core/issues/598):
+        # Although `grpc.compute_engine_channel_credentials` returns channel credentials
+        # outside of a Google Compute Engine environment (GCE), we should determine if
+        # there is a way to reliably detect a GCE environment so that
+        # `grpc.compute_engine_channel_credentials` is not called outside of GCE.
+        return grpc.compute_engine_channel_credentials(google_auth_credentials)
 
 
 def create_channel(
@@ -268,7 +309,9 @@ def create_channel(
     quota_project_id=None,
     default_scopes=None,
     default_host=None,
-    **kwargs
+    compression=None,
+    attempt_direct_path: Optional[bool] = False,
+    **kwargs,
 ):
     """Create a secure channel with credentials.
 
@@ -285,20 +328,58 @@ def create_channel(
         credentials_file (str): A file with credentials that can be loaded with
             :func:`google.auth.load_credentials_from_file`. This argument is
             mutually exclusive with credentials.
+
+            .. warning::
+                Important: If you accept a credential configuration (credential JSON/File/Stream)
+                from an external source for authentication to Google Cloud Platform, you must
+                validate it before providing it to any Google API or client library. Providing an
+                unvalidated credential configuration to Google APIs or libraries can compromise
+                the security of your systems and data. For more information, refer to
+                `Validate credential configurations from external sources`_.
+
+            .. _Validate credential configurations from external sources:
+
+            https://cloud.google.com/docs/authentication/external/externally-sourced-credentials
         quota_project_id (str): An optional project to use for billing and quota.
         default_scopes (Sequence[str]): Default scopes passed by a Google client
             library. Use 'scopes' for user-defined scopes.
         default_host (str): The default endpoint. e.g., "pubsub.googleapis.com".
+        compression (grpc.Compression): An optional value indicating the
+            compression method to be used over the lifetime of the channel.
+        attempt_direct_path (Optional[bool]): If set, Direct Path will be attempted
+            when the request is made. Direct Path is only available within a Google
+            Compute Engine (GCE) environment and provides a proxyless connection
+            which increases the available throughput, reduces latency, and increases
+            reliability. Note:
+
+            - This argument should only be set in a GCE environment and for Services
+              that are known to support Direct Path.
+            - If this argument is set outside of GCE, then this request will fail
+              unless the back-end service happens to have configured fall-back to DNS.
+            - If the request causes a `ServiceUnavailable` response, it is recommended
+              that the client repeat the request with `attempt_direct_path` set to
+              `False` as the Service may not support Direct Path.
+            - Using `ssl_credentials` with `attempt_direct_path` set to `True` will
+              result in `ValueError` as this combination  is not yet supported.
+
         kwargs: Additional key-word args passed to
             :func:`grpc_gcp.secure_channel` or :func:`grpc.secure_channel`.
+            Note: `grpc_gcp` is only supported in environments with protobuf < 4.0.0.
 
     Returns:
         grpc.Channel: The created channel.
 
     Raises:
         google.api_core.DuplicateCredentialArgs: If both a credentials object and credentials_file are passed.
+        ValueError: If `ssl_credentials` is set and `attempt_direct_path` is set to `True`.
     """
 
+    # If `ssl_credentials` is set and `attempt_direct_path` is set to `True`,
+    # raise ValueError as this is not yet supported.
+    # See https://github.com/googleapis/python-api-core/issues/590
+    if ssl_credentials and attempt_direct_path:
+        raise ValueError("Using ssl_credentials with Direct Path is not supported")
+
     composite_credentials = _create_composite_credentials(
         credentials=credentials,
         credentials_file=credentials_file,
@@ -309,16 +390,60 @@ def create_channel(
         default_host=default_host,
     )
 
-    if HAS_GRPC_GCP:
-        # If grpc_gcp module is available use grpc_gcp.secure_channel,
-        # otherwise, use grpc.secure_channel to create grpc channel.
+    # Note that grpcio-gcp is deprecated
+    if HAS_GRPC_GCP:  # pragma: NO COVER
+        if compression is not None and compression != grpc.Compression.NoCompression:
+            warnings.warn(
+                "The `compression` argument is ignored for grpc_gcp.secure_channel creation.",
+                DeprecationWarning,
+            )
+        if attempt_direct_path:
+            warnings.warn(
+                """The `attempt_direct_path` argument is ignored for grpc_gcp.secure_channel creation.""",
+                DeprecationWarning,
+            )
         return grpc_gcp.secure_channel(target, composite_credentials, **kwargs)
-    else:
-        return grpc.secure_channel(target, composite_credentials, **kwargs)
+
+    if attempt_direct_path:
+        target = _modify_target_for_direct_path(target)
+
+    return grpc.secure_channel(
+        target, composite_credentials, compression=compression, **kwargs
+    )
+
+
+def _modify_target_for_direct_path(target: str) -> str:
+    """
+    Given a target, return a modified version which is compatible with Direct Path.
+
+    Args:
+        target (str): The target service address in the format 'hostname[:port]' or
+            'dns://hostname[:port]'.
+
+    Returns:
+        target (str): The target service address which is converted into a format compatible with Direct Path.
+            If the target contains `dns:///` or does not contain `:///`, the target will be converted in
+            a format compatible with Direct Path; otherwise the original target will be returned as the
+            original target may already denote Direct Path.
+    """
+
+    # A DNS prefix may be included with the target to indicate the endpoint is living in the Internet,
+    # outside of Google Cloud Platform.
+    dns_prefix = "dns:///"
+    # Remove "dns:///" if `attempt_direct_path` is set to True as
+    # the Direct Path prefix `google-c2p:///` will be used instead.
+    target = target.replace(dns_prefix, "")
+
+    direct_path_separator = ":///"
+    if direct_path_separator not in target:
+        target_without_port = target.split(":")[0]
+        # Modify the target to use Direct Path by adding the `google-c2p:///` prefix
+        target = f"google-c2p{direct_path_separator}{target_without_port}"
+    return target
 
 
 _MethodCall = collections.namedtuple(
-    "_MethodCall", ("request", "timeout", "metadata", "credentials")
+    "_MethodCall", ("request", "timeout", "metadata", "credentials", "compression")
 )
 
 _ChannelRequest = collections.namedtuple("_ChannelRequest", ("method", "request"))
@@ -345,11 +470,15 @@ def __init__(self, method, channel):
         """List[protobuf.Message]: All requests sent to this callable."""
         self.calls = []
         """List[Tuple]: All invocations of this callable. Each tuple is the
-        request, timeout, metadata, and credentials."""
+        request, timeout, metadata, compression, and credentials."""
 
-    def __call__(self, request, timeout=None, metadata=None, credentials=None):
+    def __call__(
+        self, request, timeout=None, metadata=None, credentials=None, compression=None
+    ):
         self._channel.requests.append(_ChannelRequest(self._method, request))
-        self.calls.append(_MethodCall(request, timeout, metadata, credentials))
+        self.calls.append(
+            _MethodCall(request, timeout, metadata, credentials, compression)
+        )
         self.requests.append(request)
 
         response = self.response
@@ -464,20 +593,42 @@ def __getattr__(self, key):
         except KeyError:
             raise AttributeError
 
-    def unary_unary(self, method, request_serializer=None, response_deserializer=None):
+    def unary_unary(
+        self,
+        method,
+        request_serializer=None,
+        response_deserializer=None,
+        _registered_method=False,
+    ):
         """grpc.Channel.unary_unary implementation."""
         return self._stub_for_method(method)
 
-    def unary_stream(self, method, request_serializer=None, response_deserializer=None):
+    def unary_stream(
+        self,
+        method,
+        request_serializer=None,
+        response_deserializer=None,
+        _registered_method=False,
+    ):
         """grpc.Channel.unary_stream implementation."""
         return self._stub_for_method(method)
 
-    def stream_unary(self, method, request_serializer=None, response_deserializer=None):
+    def stream_unary(
+        self,
+        method,
+        request_serializer=None,
+        response_deserializer=None,
+        _registered_method=False,
+    ):
         """grpc.Channel.stream_unary implementation."""
         return self._stub_for_method(method)
 
     def stream_stream(
-        self, method, request_serializer=None, response_deserializer=None
+        self,
+        method,
+        request_serializer=None,
+        response_deserializer=None,
+        _registered_method=False,
     ):
         """grpc.Channel.stream_stream implementation."""
         return self._stub_for_method(method)
diff --git a/google/api_core/grpc_helpers_async.py b/google/api_core/grpc_helpers_async.py
index 92df645b..af661430 100644
--- a/google/api_core/grpc_helpers_async.py
+++ b/google/api_core/grpc_helpers_async.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-"""AsyncIO helpers for :mod:`grpc` supporting 3.6+.
+"""AsyncIO helpers for :mod:`grpc` supporting 3.7+.
 
 Please combine more detailed docstring in grpc_helpers.py to use following
 functions. This module is implementing the same surface with AsyncIO semantics.
@@ -21,14 +21,15 @@
 import asyncio
 import functools
 
+from typing import AsyncGenerator, Generic, Iterator, Optional, TypeVar
+
 import grpc
-from grpc.experimental import aio
+from grpc import aio
 
 from google.api_core import exceptions, grpc_helpers
 
-
-# TODO(lidiz) Support gRPC GCP wrapper
-HAS_GRPC_GCP = False
+# denotes the proto response type for grpc calls
+P = TypeVar("P")
 
 # NOTE(lidiz) Alternatively, we can hack "__getattribute__" to perform
 # automatic patching for us. But that means the overhead of creating an
@@ -78,8 +79,8 @@ async def wait_for_connection(self):
             raise exceptions.from_grpc_error(rpc_error) from rpc_error
 
 
-class _WrappedUnaryResponseMixin(_WrappedCall):
-    def __await__(self):
+class _WrappedUnaryResponseMixin(Generic[P], _WrappedCall):
+    def __await__(self) -> Iterator[P]:
         try:
             response = yield from self._call.__await__()
             return response
@@ -87,17 +88,17 @@ def __await__(self):
             raise exceptions.from_grpc_error(rpc_error) from rpc_error
 
 
-class _WrappedStreamResponseMixin(_WrappedCall):
+class _WrappedStreamResponseMixin(Generic[P], _WrappedCall):
     def __init__(self):
         self._wrapped_async_generator = None
 
-    async def read(self):
+    async def read(self) -> P:
         try:
             return await self._call.read()
         except grpc.RpcError as rpc_error:
             raise exceptions.from_grpc_error(rpc_error) from rpc_error
 
-    async def _wrapped_aiter(self):
+    async def _wrapped_aiter(self) -> AsyncGenerator[P, None]:
         try:
             # NOTE(lidiz) coverage doesn't understand the exception raised from
             # __anext__ method. It is covered by test case:
@@ -107,7 +108,7 @@ async def _wrapped_aiter(self):
         except grpc.RpcError as rpc_error:
             raise exceptions.from_grpc_error(rpc_error) from rpc_error
 
-    def __aiter__(self):
+    def __aiter__(self) -> AsyncGenerator[P, None]:
         if not self._wrapped_async_generator:
             self._wrapped_async_generator = self._wrapped_aiter()
         return self._wrapped_async_generator
@@ -130,29 +131,34 @@ async def done_writing(self):
 # NOTE(lidiz) Implementing each individual class separately, so we don't
 # expose any API that should not be seen. E.g., __aiter__ in unary-unary
 # RPC, or __await__ in stream-stream RPC.
-class _WrappedUnaryUnaryCall(_WrappedUnaryResponseMixin, aio.UnaryUnaryCall):
+class _WrappedUnaryUnaryCall(_WrappedUnaryResponseMixin[P], aio.UnaryUnaryCall):
     """Wrapped UnaryUnaryCall to map exceptions."""
 
 
-class _WrappedUnaryStreamCall(_WrappedStreamResponseMixin, aio.UnaryStreamCall):
+class _WrappedUnaryStreamCall(_WrappedStreamResponseMixin[P], aio.UnaryStreamCall):
     """Wrapped UnaryStreamCall to map exceptions."""
 
 
 class _WrappedStreamUnaryCall(
-    _WrappedUnaryResponseMixin, _WrappedStreamRequestMixin, aio.StreamUnaryCall
+    _WrappedUnaryResponseMixin[P], _WrappedStreamRequestMixin, aio.StreamUnaryCall
 ):
     """Wrapped StreamUnaryCall to map exceptions."""
 
 
 class _WrappedStreamStreamCall(
-    _WrappedStreamRequestMixin, _WrappedStreamResponseMixin, aio.StreamStreamCall
+    _WrappedStreamRequestMixin, _WrappedStreamResponseMixin[P], aio.StreamStreamCall
 ):
     """Wrapped StreamStreamCall to map exceptions."""
 
 
+# public type alias denoting the return type of async streaming gapic calls
+GrpcAsyncStream = _WrappedStreamResponseMixin
+# public type alias denoting the return type of unary gapic calls
+AwaitableGrpcCall = _WrappedUnaryResponseMixin
+
+
 def _wrap_unary_errors(callable_):
     """Map errors for Unary-Unary async callables."""
-    grpc_helpers._patch_callable_name(callable_)
 
     @functools.wraps(callable_)
     def error_remapped_callable(*args, **kwargs):
@@ -162,23 +168,13 @@ def error_remapped_callable(*args, **kwargs):
     return error_remapped_callable
 
 
-def _wrap_stream_errors(callable_):
+def _wrap_stream_errors(callable_, wrapper_type):
     """Map errors for streaming RPC async callables."""
-    grpc_helpers._patch_callable_name(callable_)
 
     @functools.wraps(callable_)
     async def error_remapped_callable(*args, **kwargs):
         call = callable_(*args, **kwargs)
-
-        if isinstance(call, aio.UnaryStreamCall):
-            call = _WrappedUnaryStreamCall().with_call(call)
-        elif isinstance(call, aio.StreamUnaryCall):
-            call = _WrappedStreamUnaryCall().with_call(call)
-        elif isinstance(call, aio.StreamStreamCall):
-            call = _WrappedStreamStreamCall().with_call(call)
-        else:
-            raise TypeError("Unexpected type of call %s" % type(call))
-
+        call = wrapper_type().with_call(call)
         await call.wait_for_connection()
         return call
 
@@ -200,10 +196,16 @@ def wrap_errors(callable_):
 
     Returns: Callable: The wrapped gRPC callable.
     """
-    if isinstance(callable_, aio.UnaryUnaryMultiCallable):
-        return _wrap_unary_errors(callable_)
+    grpc_helpers._patch_callable_name(callable_)
+
+    if isinstance(callable_, aio.UnaryStreamMultiCallable):
+        return _wrap_stream_errors(callable_, _WrappedUnaryStreamCall)
+    elif isinstance(callable_, aio.StreamUnaryMultiCallable):
+        return _wrap_stream_errors(callable_, _WrappedStreamUnaryCall)
+    elif isinstance(callable_, aio.StreamStreamMultiCallable):
+        return _wrap_stream_errors(callable_, _WrappedStreamStreamCall)
     else:
-        return _wrap_stream_errors(callable_)
+        return _wrap_unary_errors(callable_)
 
 
 def create_channel(
@@ -215,6 +217,8 @@ def create_channel(
     quota_project_id=None,
     default_scopes=None,
     default_host=None,
+    compression=None,
+    attempt_direct_path: Optional[bool] = False,
     **kwargs
 ):
     """Create an AsyncIO secure channel with credentials.
@@ -232,10 +236,40 @@ def create_channel(
         credentials_file (str): A file with credentials that can be loaded with
             :func:`google.auth.load_credentials_from_file`. This argument is
             mutually exclusive with credentials.
+
+            .. warning::
+                Important: If you accept a credential configuration (credential JSON/File/Stream)
+                from an external source for authentication to Google Cloud Platform, you must
+                validate it before providing it to any Google API or client library. Providing an
+                unvalidated credential configuration to Google APIs or libraries can compromise
+                the security of your systems and data. For more information, refer to
+                `Validate credential configurations from external sources`_.
+
+            .. _Validate credential configurations from external sources:
+
+            https://cloud.google.com/docs/authentication/external/externally-sourced-credentials
         quota_project_id (str): An optional project to use for billing and quota.
         default_scopes (Sequence[str]): Default scopes passed by a Google client
             library. Use 'scopes' for user-defined scopes.
         default_host (str): The default endpoint. e.g., "pubsub.googleapis.com".
+        compression (grpc.Compression): An optional value indicating the
+            compression method to be used over the lifetime of the channel.
+        attempt_direct_path (Optional[bool]): If set, Direct Path will be attempted
+            when the request is made. Direct Path is only available within a Google
+            Compute Engine (GCE) environment and provides a proxyless connection
+            which increases the available throughput, reduces latency, and increases
+            reliability. Note:
+
+            - This argument should only be set in a GCE environment and for Services
+              that are known to support Direct Path.
+            - If this argument is set outside of GCE, then this request will fail
+              unless the back-end service happens to have configured fall-back to DNS.
+            - If the request causes a `ServiceUnavailable` response, it is recommended
+              that the client repeat the request with `attempt_direct_path` set to
+              `False` as the Service may not support Direct Path.
+            - Using `ssl_credentials` with `attempt_direct_path` set to `True` will
+              result in `ValueError` as this combination  is not yet supported.
+
         kwargs: Additional key-word args passed to :func:`aio.secure_channel`.
 
     Returns:
@@ -243,8 +277,15 @@ def create_channel(
 
     Raises:
         google.api_core.DuplicateCredentialArgs: If both a credentials object and credentials_file are passed.
+        ValueError: If `ssl_credentials` is set and `attempt_direct_path` is set to `True`.
     """
 
+    # If `ssl_credentials` is set and `attempt_direct_path` is set to `True`,
+    # raise ValueError as this is not yet supported.
+    # See https://github.com/googleapis/python-api-core/issues/590
+    if ssl_credentials and attempt_direct_path:
+        raise ValueError("Using ssl_credentials with Direct Path is not supported")
+
     composite_credentials = grpc_helpers._create_composite_credentials(
         credentials=credentials,
         credentials_file=credentials_file,
@@ -255,7 +296,12 @@ def create_channel(
         default_host=default_host,
     )
 
-    return aio.secure_channel(target, composite_credentials, **kwargs)
+    if attempt_direct_path:
+        target = grpc_helpers._modify_target_for_direct_path(target)
+
+    return aio.secure_channel(
+        target, composite_credentials, compression=compression, **kwargs
+    )
 
 
 class FakeUnaryUnaryCall(_WrappedUnaryUnaryCall):
diff --git a/google/api_core/operation.py b/google/api_core/operation.py
index b17f753b..4b9c9a58 100644
--- a/google/api_core/operation.py
+++ b/google/api_core/operation.py
@@ -61,10 +61,13 @@ class Operation(polling.PollingFuture):
             result.
         metadata_type (func:`type`): The protobuf type for the operation's
             metadata.
-        retry (google.api_core.retry.Retry): The retry configuration used
-            when polling. This can be used to control how often :meth:`done`
-            is polled. Regardless of the retry's ``deadline``, it will be
-            overridden by the ``timeout`` argument to :meth:`result`.
+        polling (google.api_core.retry.Retry): The configuration used for polling.
+            This parameter controls how often :meth:`done` is polled. If the
+            ``timeout`` argument is specified in the :meth:`result` method, it will
+            override the ``polling.timeout`` property.
+        retry (google.api_core.retry.Retry): DEPRECATED: use ``polling`` instead.
+            If specified it will override ``polling`` parameter to maintain
+            backward compatibility.
     """
 
     def __init__(
@@ -74,9 +77,10 @@ def __init__(
         cancel,
         result_type,
         metadata_type=None,
-        retry=polling.DEFAULT_RETRY,
+        polling=polling.DEFAULT_POLLING,
+        **kwargs
     ):
-        super(Operation, self).__init__(retry=retry)
+        super(Operation, self).__init__(polling=polling, **kwargs)
         self._operation = operation
         self._refresh = refresh
         self._cancel = cancel
@@ -146,7 +150,7 @@ def _set_result_from_operation(self):
                 )
                 self.set_exception(exception)
 
-    def _refresh_and_update(self, retry=polling.DEFAULT_RETRY):
+    def _refresh_and_update(self, retry=None):
         """Refresh the operation and update the result if needed.
 
         Args:
@@ -155,10 +159,10 @@ def _refresh_and_update(self, retry=polling.DEFAULT_RETRY):
         # If the currently cached operation is done, no need to make another
         # RPC as it will not change once done.
         if not self._operation.done:
-            self._operation = self._refresh(retry=retry)
+            self._operation = self._refresh(retry=retry) if retry else self._refresh()
             self._set_result_from_operation()
 
-    def done(self, retry=polling.DEFAULT_RETRY):
+    def done(self, retry=None):
         """Checks to see if the operation is complete.
 
         Args:
@@ -311,10 +315,16 @@ def from_grpc(operation, operations_stub, result_type, grpc_metadata=None, **kwa
             operation.
     """
     refresh = functools.partial(
-        _refresh_grpc, operations_stub, operation.name, metadata=grpc_metadata
+        _refresh_grpc,
+        operations_stub,
+        operation.name,
+        metadata=grpc_metadata,
     )
     cancel = functools.partial(
-        _cancel_grpc, operations_stub, operation.name, metadata=grpc_metadata
+        _cancel_grpc,
+        operations_stub,
+        operation.name,
+        metadata=grpc_metadata,
     )
     return Operation(operation, refresh, cancel, result_type, **kwargs)
 
@@ -343,9 +353,13 @@ def from_gapic(operation, operations_client, result_type, grpc_metadata=None, **
             operation.
     """
     refresh = functools.partial(
-        operations_client.get_operation, operation.name, metadata=grpc_metadata
+        operations_client.get_operation,
+        operation.name,
+        metadata=grpc_metadata,
     )
     cancel = functools.partial(
-        operations_client.cancel_operation, operation.name, metadata=grpc_metadata
+        operations_client.cancel_operation,
+        operation.name,
+        metadata=grpc_metadata,
     )
     return Operation(operation, refresh, cancel, result_type, **kwargs)
diff --git a/google/api_core/operation_async.py b/google/api_core/operation_async.py
index 6bae8654..2fd341d9 100644
--- a/google/api_core/operation_async.py
+++ b/google/api_core/operation_async.py
@@ -213,9 +213,13 @@ def from_gapic(operation, operations_client, result_type, grpc_metadata=None, **
             operation.
     """
     refresh = functools.partial(
-        operations_client.get_operation, operation.name, metadata=grpc_metadata
+        operations_client.get_operation,
+        operation.name,
+        metadata=grpc_metadata,
     )
     cancel = functools.partial(
-        operations_client.cancel_operation, operation.name, metadata=grpc_metadata
+        operations_client.cancel_operation,
+        operation.name,
+        metadata=grpc_metadata,
     )
     return AsyncOperation(operation, refresh, cancel, result_type, **kwargs)
diff --git a/google/api_core/operations_v1/__init__.py b/google/api_core/operations_v1/__init__.py
index d7f963e2..4db32a4c 100644
--- a/google/api_core/operations_v1/__init__.py
+++ b/google/api_core/operations_v1/__init__.py
@@ -14,7 +14,27 @@
 
 """Package for interacting with the google.longrunning.operations meta-API."""
 
+from google.api_core.operations_v1.abstract_operations_client import AbstractOperationsClient
 from google.api_core.operations_v1.operations_async_client import OperationsAsyncClient
 from google.api_core.operations_v1.operations_client import OperationsClient
+from google.api_core.operations_v1.transports.rest import OperationsRestTransport
 
-__all__ = ["OperationsAsyncClient", "OperationsClient"]
+__all__ = [
+    "AbstractOperationsClient",
+    "OperationsAsyncClient",
+    "OperationsClient",
+    "OperationsRestTransport"
+]
+
+try:
+    from google.api_core.operations_v1.transports.rest_asyncio import (
+        AsyncOperationsRestTransport,
+    )
+    from google.api_core.operations_v1.operations_rest_client_async import AsyncOperationsRestClient
+
+    __all__ += ["AsyncOperationsRestClient", "AsyncOperationsRestTransport"]
+except ImportError:
+    # This import requires the `async_rest` extra.
+    # Don't raise an exception if `AsyncOperationsRestTransport` cannot be imported
+    # as other transports are still available.
+    pass
diff --git a/google/api_core/operations_v1/abstract_operations_base_client.py b/google/api_core/operations_v1/abstract_operations_base_client.py
new file mode 100644
index 00000000..160c2a88
--- /dev/null
+++ b/google/api_core/operations_v1/abstract_operations_base_client.py
@@ -0,0 +1,370 @@
+# -*- coding: utf-8 -*-
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from collections import OrderedDict
+import os
+import re
+from typing import Dict, Optional, Type, Union
+
+from google.api_core import client_options as client_options_lib  # type: ignore
+from google.api_core import gapic_v1  # type: ignore
+from google.api_core.operations_v1.transports.base import (
+    DEFAULT_CLIENT_INFO,
+    OperationsTransport,
+)
+from google.api_core.operations_v1.transports.rest import OperationsRestTransport
+
+try:
+    from google.api_core.operations_v1.transports.rest_asyncio import (
+        AsyncOperationsRestTransport,
+    )
+
+    HAS_ASYNC_REST_DEPENDENCIES = True
+except ImportError as e:
+    HAS_ASYNC_REST_DEPENDENCIES = False
+    ASYNC_REST_EXCEPTION = e
+
+from google.auth import credentials as ga_credentials  # type: ignore
+from google.auth.exceptions import MutualTLSChannelError  # type: ignore
+from google.auth.transport import mtls  # type: ignore
+
+
+class AbstractOperationsBaseClientMeta(type):
+    """Metaclass for the Operations Base client.
+
+    This provides base class-level methods for building and retrieving
+    support objects (e.g. transport) without polluting the client instance
+    objects.
+    """
+
+    _transport_registry = OrderedDict()  # type: Dict[str, Type[OperationsTransport]]
+    _transport_registry["rest"] = OperationsRestTransport
+    if HAS_ASYNC_REST_DEPENDENCIES:
+        _transport_registry["rest_asyncio"] = AsyncOperationsRestTransport
+
+    def get_transport_class(
+        cls,
+        label: Optional[str] = None,
+    ) -> Type[OperationsTransport]:
+        """Returns an appropriate transport class.
+
+        Args:
+            label: The name of the desired transport. If none is
+                provided, then the first transport in the registry is used.
+
+        Returns:
+            The transport class to use.
+        """
+        # If a specific transport is requested, return that one.
+        if (
+            label == "rest_asyncio" and not HAS_ASYNC_REST_DEPENDENCIES
+        ):  # pragma: NO COVER
+            raise ASYNC_REST_EXCEPTION
+
+        if label:
+            return cls._transport_registry[label]
+
+        # No transport is requested; return the default (that is, the first one
+        # in the dictionary).
+        return next(iter(cls._transport_registry.values()))
+
+
+class AbstractOperationsBaseClient(metaclass=AbstractOperationsBaseClientMeta):
+    """Manages long-running operations with an API service.
+
+    When an API method normally takes long time to complete, it can be
+    designed to return [Operation][google.api_core.operations_v1.Operation] to the
+    client, and the client can use this interface to receive the real
+    response asynchronously by polling the operation resource, or pass
+    the operation resource to another API (such as Google Cloud Pub/Sub
+    API) to receive the response. Any API service that returns
+    long-running operations should implement the ``Operations``
+    interface so developers can have a consistent client experience.
+    """
+
+    @staticmethod
+    def _get_default_mtls_endpoint(api_endpoint):
+        """Converts api endpoint to mTLS endpoint.
+
+        Convert "*.sandbox.googleapis.com" and "*.googleapis.com" to
+        "*.mtls.sandbox.googleapis.com" and "*.mtls.googleapis.com" respectively.
+        Args:
+            api_endpoint (Optional[str]): the api endpoint to convert.
+        Returns:
+            str: converted mTLS api endpoint.
+        """
+        if not api_endpoint:
+            return api_endpoint
+
+        mtls_endpoint_re = re.compile(
+            r"(?P<name>[^.]+)(?P<mtls>\.mtls)?(?P<sandbox>\.sandbox)?(?P<googledomain>\.googleapis\.com)?"
+        )
+
+        m = mtls_endpoint_re.match(api_endpoint)
+        name, mtls, sandbox, googledomain = m.groups()
+        if mtls or not googledomain:
+            return api_endpoint
+
+        if sandbox:
+            return api_endpoint.replace(
+                "sandbox.googleapis.com", "mtls.sandbox.googleapis.com"
+            )
+
+        return api_endpoint.replace(".googleapis.com", ".mtls.googleapis.com")
+
+    DEFAULT_ENDPOINT = "longrunning.googleapis.com"
+    DEFAULT_MTLS_ENDPOINT = _get_default_mtls_endpoint.__func__(  # type: ignore
+        DEFAULT_ENDPOINT
+    )
+
+    @classmethod
+    def from_service_account_info(cls, info: dict, *args, **kwargs):
+        """
+        This class method should be overridden by the subclasses.
+
+        Args:
+            info (dict): The service account private key info.
+            args: Additional arguments to pass to the constructor.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Raises:
+            NotImplementedError: If the method is called on the base class.
+        """
+        raise NotImplementedError("`from_service_account_info` is not implemented.")
+
+    @classmethod
+    def from_service_account_file(cls, filename: str, *args, **kwargs):
+        """
+        This class method should be overridden by the subclasses.
+
+        Args:
+            filename (str): The path to the service account private key json
+                file.
+            args: Additional arguments to pass to the constructor.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Raises:
+            NotImplementedError: If the method is called on the base class.
+        """
+        raise NotImplementedError("`from_service_account_file` is not implemented.")
+
+    from_service_account_json = from_service_account_file
+
+    @property
+    def transport(self) -> OperationsTransport:
+        """Returns the transport used by the client instance.
+
+        Returns:
+            OperationsTransport: The transport used by the client
+                instance.
+        """
+        return self._transport
+
+    @staticmethod
+    def common_billing_account_path(
+        billing_account: str,
+    ) -> str:
+        """Returns a fully-qualified billing_account string."""
+        return "billingAccounts/{billing_account}".format(
+            billing_account=billing_account,
+        )
+
+    @staticmethod
+    def parse_common_billing_account_path(path: str) -> Dict[str, str]:
+        """Parse a billing_account path into its component segments."""
+        m = re.match(r"^billingAccounts/(?P<billing_account>.+?)$", path)
+        return m.groupdict() if m else {}
+
+    @staticmethod
+    def common_folder_path(
+        folder: str,
+    ) -> str:
+        """Returns a fully-qualified folder string."""
+        return "folders/{folder}".format(
+            folder=folder,
+        )
+
+    @staticmethod
+    def parse_common_folder_path(path: str) -> Dict[str, str]:
+        """Parse a folder path into its component segments."""
+        m = re.match(r"^folders/(?P<folder>.+?)$", path)
+        return m.groupdict() if m else {}
+
+    @staticmethod
+    def common_organization_path(
+        organization: str,
+    ) -> str:
+        """Returns a fully-qualified organization string."""
+        return "organizations/{organization}".format(
+            organization=organization,
+        )
+
+    @staticmethod
+    def parse_common_organization_path(path: str) -> Dict[str, str]:
+        """Parse a organization path into its component segments."""
+        m = re.match(r"^organizations/(?P<organization>.+?)$", path)
+        return m.groupdict() if m else {}
+
+    @staticmethod
+    def common_project_path(
+        project: str,
+    ) -> str:
+        """Returns a fully-qualified project string."""
+        return "projects/{project}".format(
+            project=project,
+        )
+
+    @staticmethod
+    def parse_common_project_path(path: str) -> Dict[str, str]:
+        """Parse a project path into its component segments."""
+        m = re.match(r"^projects/(?P<project>.+?)$", path)
+        return m.groupdict() if m else {}
+
+    @staticmethod
+    def common_location_path(
+        project: str,
+        location: str,
+    ) -> str:
+        """Returns a fully-qualified location string."""
+        return "projects/{project}/locations/{location}".format(
+            project=project,
+            location=location,
+        )
+
+    @staticmethod
+    def parse_common_location_path(path: str) -> Dict[str, str]:
+        """Parse a location path into its component segments."""
+        m = re.match(r"^projects/(?P<project>.+?)/locations/(?P<location>.+?)$", path)
+        return m.groupdict() if m else {}
+
+    def __init__(
+        self,
+        *,
+        credentials: Optional[ga_credentials.Credentials] = None,
+        transport: Union[str, OperationsTransport, None] = None,
+        client_options: Optional[client_options_lib.ClientOptions] = None,
+        client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+    ) -> None:
+        """Instantiates the operations client.
+
+        Args:
+            credentials (Optional[google.auth.credentials.Credentials]): The
+                authorization credentials to attach to requests. These
+                credentials identify the application to the service; if none
+                are specified, the client will attempt to ascertain the
+                credentials from the environment.
+            transport (Union[str, OperationsTransport]): The
+                transport to use. If set to None, a transport is chosen
+                automatically.
+            client_options (google.api_core.client_options.ClientOptions): Custom options for the
+                client. It won't take effect if a ``transport`` instance is provided.
+                (1) The ``api_endpoint`` property can be used to override the
+                default endpoint provided by the client. GOOGLE_API_USE_MTLS_ENDPOINT
+                environment variable can also be used to override the endpoint:
+                "always" (always use the default mTLS endpoint), "never" (always
+                use the default regular endpoint) and "auto" (auto switch to the
+                default mTLS endpoint if client certificate is present, this is
+                the default value). However, the ``api_endpoint`` property takes
+                precedence if provided.
+                (2) If GOOGLE_API_USE_CLIENT_CERTIFICATE environment variable
+                is "true", then the ``client_cert_source`` property can be used
+                to provide client certificate for mutual TLS transport. If
+                not provided, the default SSL client certificate will be used if
+                present. If GOOGLE_API_USE_CLIENT_CERTIFICATE is "false" or not
+                set, no client certificate will be used.
+            client_info (google.api_core.gapic_v1.client_info.ClientInfo):
+                The client info used to send a user-agent string along with
+                API requests. If ``None``, then default info will be used.
+                Generally, you only need to set this if you're developing
+                your own client library.
+
+        Raises:
+            google.auth.exceptions.MutualTLSChannelError: If mutual TLS transport
+                creation failed for any reason.
+        """
+        if isinstance(client_options, dict):
+            client_options = client_options_lib.from_dict(client_options)
+        if client_options is None:
+            client_options = client_options_lib.ClientOptions()
+
+        # Create SSL credentials for mutual TLS if needed.
+        use_client_cert = os.getenv(
+            "GOOGLE_API_USE_CLIENT_CERTIFICATE", "false"
+        ).lower()
+        if use_client_cert not in ("true", "false"):
+            raise ValueError(
+                "Environment variable `GOOGLE_API_USE_CLIENT_CERTIFICATE` must be either `true` or `false`"
+            )
+        client_cert_source_func = None
+        is_mtls = False
+        if use_client_cert == "true":
+            if client_options.client_cert_source:
+                is_mtls = True
+                client_cert_source_func = client_options.client_cert_source
+            else:
+                is_mtls = mtls.has_default_client_cert_source()
+                if is_mtls:
+                    client_cert_source_func = mtls.default_client_cert_source()
+                else:
+                    client_cert_source_func = None
+
+        # Figure out which api endpoint to use.
+        if client_options.api_endpoint is not None:
+            api_endpoint = client_options.api_endpoint
+        else:
+            use_mtls_env = os.getenv("GOOGLE_API_USE_MTLS_ENDPOINT", "auto")
+            if use_mtls_env == "never":
+                api_endpoint = self.DEFAULT_ENDPOINT
+            elif use_mtls_env == "always":
+                api_endpoint = self.DEFAULT_MTLS_ENDPOINT
+            elif use_mtls_env == "auto":
+                if is_mtls:
+                    api_endpoint = self.DEFAULT_MTLS_ENDPOINT
+                else:
+                    api_endpoint = self.DEFAULT_ENDPOINT
+            else:
+                raise MutualTLSChannelError(
+                    "Unsupported GOOGLE_API_USE_MTLS_ENDPOINT value. Accepted "
+                    "values: never, auto, always"
+                )
+
+        # Save or instantiate the transport.
+        # Ordinarily, we provide the transport, but allowing a custom transport
+        # instance provides an extensibility point for unusual situations.
+        if isinstance(transport, OperationsTransport):
+            # transport is a OperationsTransport instance.
+            if credentials or client_options.credentials_file:
+                raise ValueError(
+                    "When providing a transport instance, "
+                    "provide its credentials directly."
+                )
+            if client_options.scopes:
+                raise ValueError(
+                    "When providing a transport instance, provide its scopes "
+                    "directly."
+                )
+            self._transport = transport
+        else:
+            Transport = type(self).get_transport_class(transport)
+            self._transport = Transport(
+                credentials=credentials,
+                credentials_file=client_options.credentials_file,
+                host=api_endpoint,
+                scopes=client_options.scopes,
+                client_cert_source_for_mtls=client_cert_source_func,
+                quota_project_id=client_options.quota_project_id,
+                client_info=client_info,
+                always_use_jwt_access=True,
+            )
diff --git a/google/api_core/operations_v1/abstract_operations_client.py b/google/api_core/operations_v1/abstract_operations_client.py
new file mode 100644
index 00000000..fc445362
--- /dev/null
+++ b/google/api_core/operations_v1/abstract_operations_client.py
@@ -0,0 +1,387 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+from typing import Optional, Sequence, Tuple, Union
+
+from google.api_core import client_options as client_options_lib  # type: ignore
+from google.api_core import gapic_v1  # type: ignore
+from google.api_core import retry as retries  # type: ignore
+from google.api_core.operations_v1 import pagers
+from google.api_core.operations_v1.transports.base import (
+    DEFAULT_CLIENT_INFO,
+    OperationsTransport,
+)
+from google.api_core.operations_v1.abstract_operations_base_client import (
+    AbstractOperationsBaseClient,
+)
+from google.auth import credentials as ga_credentials  # type: ignore
+from google.longrunning import operations_pb2
+from google.oauth2 import service_account  # type: ignore
+import grpc
+
+OptionalRetry = Union[retries.Retry, object]
+
+
+class AbstractOperationsClient(AbstractOperationsBaseClient):
+    """Manages long-running operations with an API service.
+
+    When an API method normally takes long time to complete, it can be
+    designed to return [Operation][google.api_core.operations_v1.Operation] to the
+    client, and the client can use this interface to receive the real
+    response asynchronously by polling the operation resource, or pass
+    the operation resource to another API (such as Google Cloud Pub/Sub
+    API) to receive the response. Any API service that returns
+    long-running operations should implement the ``Operations``
+    interface so developers can have a consistent client experience.
+    """
+
+    def __init__(
+        self,
+        *,
+        credentials: Optional[ga_credentials.Credentials] = None,
+        transport: Union[str, OperationsTransport, None] = None,
+        client_options: Optional[client_options_lib.ClientOptions] = None,
+        client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+    ) -> None:
+        """Instantiates the operations client.
+
+        Args:
+            credentials (Optional[google.auth.credentials.Credentials]): The
+                authorization credentials to attach to requests. These
+                credentials identify the application to the service; if none
+                are specified, the client will attempt to ascertain the
+                credentials from the environment.
+            transport (Union[str, OperationsTransport]): The
+                transport to use. If set to None, a transport is chosen
+                automatically.
+            client_options (google.api_core.client_options.ClientOptions): Custom options for the
+                client. It won't take effect if a ``transport`` instance is provided.
+                (1) The ``api_endpoint`` property can be used to override the
+                default endpoint provided by the client. GOOGLE_API_USE_MTLS_ENDPOINT
+                environment variable can also be used to override the endpoint:
+                "always" (always use the default mTLS endpoint), "never" (always
+                use the default regular endpoint) and "auto" (auto switch to the
+                default mTLS endpoint if client certificate is present, this is
+                the default value). However, the ``api_endpoint`` property takes
+                precedence if provided.
+                (2) If GOOGLE_API_USE_CLIENT_CERTIFICATE environment variable
+                is "true", then the ``client_cert_source`` property can be used
+                to provide client certificate for mutual TLS transport. If
+                not provided, the default SSL client certificate will be used if
+                present. If GOOGLE_API_USE_CLIENT_CERTIFICATE is "false" or not
+                set, no client certificate will be used.
+            client_info (google.api_core.gapic_v1.client_info.ClientInfo):
+                The client info used to send a user-agent string along with
+                API requests. If ``None``, then default info will be used.
+                Generally, you only need to set this if you're developing
+                your own client library.
+
+        Raises:
+            google.auth.exceptions.MutualTLSChannelError: If mutual TLS transport
+                creation failed for any reason.
+        """
+        super().__init__(
+            credentials=credentials,
+            transport=transport,
+            client_options=client_options,
+            client_info=client_info,
+        )
+
+    @classmethod
+    def from_service_account_info(cls, info: dict, *args, **kwargs):
+        """Creates an instance of this client using the provided credentials
+            info.
+
+        Args:
+            info (dict): The service account private key info.
+            args: Additional arguments to pass to the constructor.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Returns:
+            AbstractOperationsClient: The constructed client.
+        """
+        credentials = service_account.Credentials.from_service_account_info(info)
+        kwargs["credentials"] = credentials
+        return cls(*args, **kwargs)
+
+    @classmethod
+    def from_service_account_file(cls, filename: str, *args, **kwargs):
+        """Creates an instance of this client using the provided credentials
+            file.
+
+        Args:
+            filename (str): The path to the service account private key json
+                file.
+            args: Additional arguments to pass to the constructor.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Returns:
+            AbstractOperationsClient: The constructed client.
+        """
+        credentials = service_account.Credentials.from_service_account_file(filename)
+        kwargs["credentials"] = credentials
+        return cls(*args, **kwargs)
+
+    from_service_account_json = from_service_account_file
+
+    def list_operations(
+        self,
+        name: str,
+        filter_: Optional[str] = None,
+        *,
+        page_size: Optional[int] = None,
+        page_token: Optional[str] = None,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
+        timeout: Optional[float] = None,
+        compression: Optional[grpc.Compression] = gapic_v1.method.DEFAULT,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> pagers.ListOperationsPager:
+        r"""Lists operations that match the specified filter in the request.
+        If the server doesn't support this method, it returns
+        ``UNIMPLEMENTED``.
+
+        NOTE: the ``name`` binding allows API services to override the
+        binding to use different resource name schemes, such as
+        ``users/*/operations``. To override the binding, API services
+        can add a binding such as ``"/v1/{name=users/*}/operations"`` to
+        their service configuration. For backwards compatibility, the
+        default name includes the operations collection id, however
+        overriding users must ensure the name binding is the parent
+        resource, without the operations collection id.
+
+        Args:
+            name (str):
+                The name of the operation's parent
+                resource.
+            filter_ (str):
+                The standard list filter.
+                This corresponds to the ``filter`` field
+                on the ``request`` instance; if ``request`` is provided, this
+                should not be set.
+            retry (google.api_core.retry.Retry): Designation of what errors, if any,
+                should be retried.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+
+        Returns:
+            google.api_core.operations_v1.pagers.ListOperationsPager:
+                The response message for
+                [Operations.ListOperations][google.api_core.operations_v1.Operations.ListOperations].
+
+                Iterating over this object will yield results and
+                resolve additional pages automatically.
+
+        """
+        # Create a protobuf request object.
+        request = operations_pb2.ListOperationsRequest(name=name, filter=filter_)
+        if page_size is not None:
+            request.page_size = page_size
+        if page_token is not None:
+            request.page_token = page_token
+
+        # Wrap the RPC method; this adds retry and timeout information,
+        # and friendly error handling.
+        rpc = self._transport._wrapped_methods[self._transport.list_operations]
+
+        # Certain fields should be provided within the metadata header;
+        # add these here.
+        metadata = tuple(metadata or ()) + (
+            gapic_v1.routing_header.to_grpc_metadata((("name", request.name),)),
+        )
+
+        # Send the request.
+        response = rpc(
+            request,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
+        )
+
+        # This method is paged; wrap the response in a pager, which provides
+        # an `__iter__` convenience method.
+        response = pagers.ListOperationsPager(
+            method=rpc,
+            request=request,
+            response=response,
+            metadata=metadata,
+        )
+
+        # Done; return the response.
+        return response
+
+    def get_operation(
+        self,
+        name: str,
+        *,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
+        timeout: Optional[float] = None,
+        compression: Optional[grpc.Compression] = gapic_v1.method.DEFAULT,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> operations_pb2.Operation:
+        r"""Gets the latest state of a long-running operation.
+        Clients can use this method to poll the operation result
+        at intervals as recommended by the API service.
+
+        Args:
+            name (str):
+                The name of the operation resource.
+            retry (google.api_core.retry.Retry): Designation of what errors, if any,
+                should be retried.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+
+        Returns:
+            google.longrunning.operations_pb2.Operation:
+                This resource represents a long-
+                running operation that is the result of a
+                network API call.
+
+        """
+
+        request = operations_pb2.GetOperationRequest(name=name)
+
+        # Wrap the RPC method; this adds retry and timeout information,
+        # and friendly error handling.
+        rpc = self._transport._wrapped_methods[self._transport.get_operation]
+
+        # Certain fields should be provided within the metadata header;
+        # add these here.
+        metadata = tuple(metadata or ()) + (
+            gapic_v1.routing_header.to_grpc_metadata((("name", request.name),)),
+        )
+
+        # Send the request.
+        response = rpc(
+            request,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
+        )
+
+        # Done; return the response.
+        return response
+
+    def delete_operation(
+        self,
+        name: str,
+        *,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
+        timeout: Optional[float] = None,
+        compression: Optional[grpc.Compression] = gapic_v1.method.DEFAULT,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> None:
+        r"""Deletes a long-running operation. This method indicates that the
+        client is no longer interested in the operation result. It does
+        not cancel the operation. If the server doesn't support this
+        method, it returns ``google.rpc.Code.UNIMPLEMENTED``.
+
+        Args:
+            name (str):
+                The name of the operation resource to
+                be deleted.
+
+                This corresponds to the ``name`` field
+                on the ``request`` instance; if ``request`` is provided, this
+                should not be set.
+            retry (google.api_core.retry.Retry): Designation of what errors, if any,
+                should be retried.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+        """
+        # Create the request object.
+        request = operations_pb2.DeleteOperationRequest(name=name)
+
+        # Wrap the RPC method; this adds retry and timeout information,
+        # and friendly error handling.
+        rpc = self._transport._wrapped_methods[self._transport.delete_operation]
+
+        # Certain fields should be provided within the metadata header;
+        # add these here.
+        metadata = tuple(metadata or ()) + (
+            gapic_v1.routing_header.to_grpc_metadata((("name", request.name),)),
+        )
+
+        # Send the request.
+        rpc(
+            request,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
+        )
+
+    def cancel_operation(
+        self,
+        name: Optional[str] = None,
+        *,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
+        timeout: Optional[float] = None,
+        compression: Optional[grpc.Compression] = gapic_v1.method.DEFAULT,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> None:
+        r"""Starts asynchronous cancellation on a long-running operation.
+        The server makes a best effort to cancel the operation, but
+        success is not guaranteed. If the server doesn't support this
+        method, it returns ``google.rpc.Code.UNIMPLEMENTED``. Clients
+        can use
+        [Operations.GetOperation][google.api_core.operations_v1.Operations.GetOperation]
+        or other methods to check whether the cancellation succeeded or
+        whether the operation completed despite cancellation. On
+        successful cancellation, the operation is not deleted; instead,
+        it becomes an operation with an
+        [Operation.error][google.api_core.operations_v1.Operation.error] value with
+        a [google.rpc.Status.code][google.rpc.Status.code] of 1,
+        corresponding to ``Code.CANCELLED``.
+
+        Args:
+            name (str):
+                The name of the operation resource to
+                be cancelled.
+
+                This corresponds to the ``name`` field
+                on the ``request`` instance; if ``request`` is provided, this
+                should not be set.
+            retry (google.api_core.retry.Retry): Designation of what errors, if any,
+                should be retried.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+        """
+        # Create the request object.
+        request = operations_pb2.CancelOperationRequest(name=name)
+
+        # Wrap the RPC method; this adds retry and timeout information,
+        # and friendly error handling.
+        rpc = self._transport._wrapped_methods[self._transport.cancel_operation]
+
+        # Certain fields should be provided within the metadata header;
+        # add these here.
+        metadata = tuple(metadata or ()) + (
+            gapic_v1.routing_header.to_grpc_metadata((("name", request.name),)),
+        )
+
+        # Send the request.
+        rpc(
+            request,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
+        )
diff --git a/google/api_core/operations_v1/operations_async_client.py b/google/api_core/operations_v1/operations_async_client.py
index 5a5e5562..a60c7177 100644
--- a/google/api_core/operations_v1/operations_async_client.py
+++ b/google/api_core/operations_v1/operations_async_client.py
@@ -24,9 +24,12 @@
 
 import functools
 
+from google.api_core import exceptions as core_exceptions
 from google.api_core import gapic_v1, page_iterator_async
-from google.api_core.operations_v1 import operations_client_config
+from google.api_core import retry_async as retries
+from google.api_core import timeout as timeouts
 from google.longrunning import operations_pb2
+from grpc import Compression
 
 
 class OperationsAsyncClient:
@@ -41,39 +44,50 @@ class OperationsAsyncClient:
             the default configuration is used.
     """
 
-    def __init__(self, channel, client_config=operations_client_config.config):
+    def __init__(self, channel, client_config=None):
         # Create the gRPC client stub with gRPC AsyncIO channel.
         self.operations_stub = operations_pb2.OperationsStub(channel)
 
-        # Create all wrapped methods using the interface configuration.
-        # The interface config contains all of the default settings for retry
-        # and timeout for each RPC method.
-        interfaces = client_config["interfaces"]
-        interface_config = interfaces["google.longrunning.Operations"]
-        method_configs = gapic_v1.config_async.parse_method_configs(interface_config)
+        default_retry = retries.AsyncRetry(
+            initial=0.1,  # seconds
+            maximum=60.0,  # seconds
+            multiplier=1.3,
+            predicate=retries.if_exception_type(
+                core_exceptions.DeadlineExceeded,
+                core_exceptions.ServiceUnavailable,
+            ),
+            timeout=600.0,  # seconds
+        )
+        default_timeout = timeouts.TimeToDeadlineTimeout(timeout=600.0)
+
+        default_compression = Compression.NoCompression
 
         self._get_operation = gapic_v1.method_async.wrap_method(
             self.operations_stub.GetOperation,
-            default_retry=method_configs["GetOperation"].retry,
-            default_timeout=method_configs["GetOperation"].timeout,
+            default_retry=default_retry,
+            default_timeout=default_timeout,
+            default_compression=default_compression,
         )
 
         self._list_operations = gapic_v1.method_async.wrap_method(
             self.operations_stub.ListOperations,
-            default_retry=method_configs["ListOperations"].retry,
-            default_timeout=method_configs["ListOperations"].timeout,
+            default_retry=default_retry,
+            default_timeout=default_timeout,
+            default_compression=default_compression,
         )
 
         self._cancel_operation = gapic_v1.method_async.wrap_method(
             self.operations_stub.CancelOperation,
-            default_retry=method_configs["CancelOperation"].retry,
-            default_timeout=method_configs["CancelOperation"].timeout,
+            default_retry=default_retry,
+            default_timeout=default_timeout,
+            default_compression=default_compression,
         )
 
         self._delete_operation = gapic_v1.method_async.wrap_method(
             self.operations_stub.DeleteOperation,
-            default_retry=method_configs["DeleteOperation"].retry,
-            default_timeout=method_configs["DeleteOperation"].timeout,
+            default_retry=default_retry,
+            default_timeout=default_timeout,
+            default_compression=default_compression,
         )
 
     async def get_operation(
@@ -81,6 +95,7 @@ async def get_operation(
         name,
         retry=gapic_v1.method_async.DEFAULT,
         timeout=gapic_v1.method_async.DEFAULT,
+        compression=gapic_v1.method_async.DEFAULT,
         metadata=None,
     ):
         """Gets the latest state of a long-running operation.
@@ -107,6 +122,8 @@ async def get_operation(
                 unspecified, the the default timeout in the client
                 configuration is used. If ``None``, then the RPC method will
                 not time out.
+            compression (grpc.Compression): An element of grpc.compression
+                e.g. grpc.compression.Gzip.
             metadata (Optional[List[Tuple[str, str]]]):
                 Additional gRPC metadata.
 
@@ -126,7 +143,11 @@ async def get_operation(
         metadata.append(gapic_v1.routing_header.to_grpc_metadata({"name": name}))
 
         return await self._get_operation(
-            request, retry=retry, timeout=timeout, metadata=metadata
+            request,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
         )
 
     async def list_operations(
@@ -135,6 +156,7 @@ async def list_operations(
         filter_,
         retry=gapic_v1.method_async.DEFAULT,
         timeout=gapic_v1.method_async.DEFAULT,
+        compression=gapic_v1.method_async.DEFAULT,
         metadata=None,
     ):
         """
@@ -171,6 +193,8 @@ async def list_operations(
                 unspecified, the the default timeout in the client
                 configuration is used. If ``None``, then the RPC method will
                 not time out.
+            compression (grpc.Compression): An element of grpc.compression
+                e.g. grpc.compression.Gzip.
             metadata (Optional[List[Tuple[str, str]]]): Additional gRPC
                 metadata.
 
@@ -195,7 +219,11 @@ async def list_operations(
 
         # Create the method used to fetch pages
         method = functools.partial(
-            self._list_operations, retry=retry, timeout=timeout, metadata=metadata
+            self._list_operations,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
         )
 
         iterator = page_iterator_async.AsyncGRPCIterator(
@@ -214,6 +242,7 @@ async def cancel_operation(
         name,
         retry=gapic_v1.method_async.DEFAULT,
         timeout=gapic_v1.method_async.DEFAULT,
+        compression=gapic_v1.method_async.DEFAULT,
         metadata=None,
     ):
         """Starts asynchronous cancellation on a long-running operation.
@@ -254,6 +283,8 @@ async def cancel_operation(
             google.api_core.exceptions.GoogleAPICallError: If an error occurred
                 while invoking the RPC, the appropriate ``GoogleAPICallError``
                 subclass will be raised.
+            compression (grpc.Compression): An element of grpc.compression
+                e.g. grpc.compression.Gzip.
             metadata (Optional[List[Tuple[str, str]]]): Additional gRPC
                 metadata.
         """
@@ -265,7 +296,11 @@ async def cancel_operation(
         metadata.append(gapic_v1.routing_header.to_grpc_metadata({"name": name}))
 
         await self._cancel_operation(
-            request, retry=retry, timeout=timeout, metadata=metadata
+            request,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
         )
 
     async def delete_operation(
@@ -273,6 +308,7 @@ async def delete_operation(
         name,
         retry=gapic_v1.method_async.DEFAULT,
         timeout=gapic_v1.method_async.DEFAULT,
+        compression=gapic_v1.method_async.DEFAULT,
         metadata=None,
     ):
         """Deletes a long-running operation.
@@ -299,6 +335,8 @@ async def delete_operation(
                 unspecified, the the default timeout in the client
                 configuration is used. If ``None``, then the RPC method will
                 not time out.
+            compression (grpc.Compression): An element of grpc.compression
+                e.g. grpc.compression.Gzip.
             metadata (Optional[List[Tuple[str, str]]]): Additional gRPC
                 metadata.
 
@@ -318,5 +356,9 @@ async def delete_operation(
         metadata.append(gapic_v1.routing_header.to_grpc_metadata({"name": name}))
 
         await self._delete_operation(
-            request, retry=retry, timeout=timeout, metadata=metadata
+            request,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
         )
diff --git a/google/api_core/operations_v1/operations_client.py b/google/api_core/operations_v1/operations_client.py
index e48eac01..d1d3fd55 100644
--- a/google/api_core/operations_v1/operations_client.py
+++ b/google/api_core/operations_v1/operations_client.py
@@ -37,10 +37,13 @@
 
 import functools
 
+from google.api_core import exceptions as core_exceptions
 from google.api_core import gapic_v1
 from google.api_core import page_iterator
-from google.api_core.operations_v1 import operations_client_config
+from google.api_core import retry as retries
+from google.api_core import timeout as timeouts
 from google.longrunning import operations_pb2
+from grpc import Compression
 
 
 class OperationsClient(object):
@@ -54,39 +57,50 @@ class OperationsClient(object):
             the default configuration is used.
     """
 
-    def __init__(self, channel, client_config=operations_client_config.config):
+    def __init__(self, channel, client_config=None):
         # Create the gRPC client stub.
         self.operations_stub = operations_pb2.OperationsStub(channel)
 
-        # Create all wrapped methods using the interface configuration.
-        # The interface config contains all of the default settings for retry
-        # and timeout for each RPC method.
-        interfaces = client_config["interfaces"]
-        interface_config = interfaces["google.longrunning.Operations"]
-        method_configs = gapic_v1.config.parse_method_configs(interface_config)
+        default_retry = retries.Retry(
+            initial=0.1,  # seconds
+            maximum=60.0,  # seconds
+            multiplier=1.3,
+            predicate=retries.if_exception_type(
+                core_exceptions.DeadlineExceeded,
+                core_exceptions.ServiceUnavailable,
+            ),
+            timeout=600.0,  # seconds
+        )
+        default_timeout = timeouts.TimeToDeadlineTimeout(timeout=600.0)
+
+        default_compression = Compression.NoCompression
 
         self._get_operation = gapic_v1.method.wrap_method(
             self.operations_stub.GetOperation,
-            default_retry=method_configs["GetOperation"].retry,
-            default_timeout=method_configs["GetOperation"].timeout,
+            default_retry=default_retry,
+            default_timeout=default_timeout,
+            default_compression=default_compression,
         )
 
         self._list_operations = gapic_v1.method.wrap_method(
             self.operations_stub.ListOperations,
-            default_retry=method_configs["ListOperations"].retry,
-            default_timeout=method_configs["ListOperations"].timeout,
+            default_retry=default_retry,
+            default_timeout=default_timeout,
+            default_compression=default_compression,
         )
 
         self._cancel_operation = gapic_v1.method.wrap_method(
             self.operations_stub.CancelOperation,
-            default_retry=method_configs["CancelOperation"].retry,
-            default_timeout=method_configs["CancelOperation"].timeout,
+            default_retry=default_retry,
+            default_timeout=default_timeout,
+            default_compression=default_compression,
         )
 
         self._delete_operation = gapic_v1.method.wrap_method(
             self.operations_stub.DeleteOperation,
-            default_retry=method_configs["DeleteOperation"].retry,
-            default_timeout=method_configs["DeleteOperation"].timeout,
+            default_retry=default_retry,
+            default_timeout=default_timeout,
+            default_compression=default_compression,
         )
 
     # Service calls
@@ -95,6 +109,7 @@ def get_operation(
         name,
         retry=gapic_v1.method.DEFAULT,
         timeout=gapic_v1.method.DEFAULT,
+        compression=gapic_v1.method.DEFAULT,
         metadata=None,
     ):
         """Gets the latest state of a long-running operation.
@@ -121,6 +136,8 @@ def get_operation(
                 unspecified, the the default timeout in the client
                 configuration is used. If ``None``, then the RPC method will
                 not time out.
+            compression (grpc.Compression): An element of grpc.compression
+                e.g. grpc.compression.Gzip.
             metadata (Optional[List[Tuple[str, str]]]):
                 Additional gRPC metadata.
 
@@ -140,7 +157,11 @@ def get_operation(
         metadata.append(gapic_v1.routing_header.to_grpc_metadata({"name": name}))
 
         return self._get_operation(
-            request, retry=retry, timeout=timeout, metadata=metadata
+            request,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
         )
 
     def list_operations(
@@ -149,6 +170,7 @@ def list_operations(
         filter_,
         retry=gapic_v1.method.DEFAULT,
         timeout=gapic_v1.method.DEFAULT,
+        compression=gapic_v1.method.DEFAULT,
         metadata=None,
     ):
         """
@@ -185,6 +207,8 @@ def list_operations(
                 unspecified, the the default timeout in the client
                 configuration is used. If ``None``, then the RPC method will
                 not time out.
+            compression (grpc.Compression): An element of grpc.compression
+                e.g. grpc.compression.Gzip.
             metadata (Optional[List[Tuple[str, str]]]): Additional gRPC
                 metadata.
 
@@ -209,7 +233,11 @@ def list_operations(
 
         # Create the method used to fetch pages
         method = functools.partial(
-            self._list_operations, retry=retry, timeout=timeout, metadata=metadata
+            self._list_operations,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
         )
 
         iterator = page_iterator.GRPCIterator(
@@ -228,6 +256,7 @@ def cancel_operation(
         name,
         retry=gapic_v1.method.DEFAULT,
         timeout=gapic_v1.method.DEFAULT,
+        compression=gapic_v1.method.DEFAULT,
         metadata=None,
     ):
         """Starts asynchronous cancellation on a long-running operation.
@@ -260,6 +289,8 @@ def cancel_operation(
                 unspecified, the the default timeout in the client
                 configuration is used. If ``None``, then the RPC method will
                 not time out.
+            compression (grpc.Compression): An element of grpc.compression
+                e.g. grpc.compression.Gzip.
             metadata (Optional[List[Tuple[str, str]]]): Additional gRPC
                 metadata.
 
@@ -278,13 +309,20 @@ def cancel_operation(
         metadata = metadata or []
         metadata.append(gapic_v1.routing_header.to_grpc_metadata({"name": name}))
 
-        self._cancel_operation(request, retry=retry, timeout=timeout, metadata=metadata)
+        self._cancel_operation(
+            request,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
+        )
 
     def delete_operation(
         self,
         name,
         retry=gapic_v1.method.DEFAULT,
         timeout=gapic_v1.method.DEFAULT,
+        compression=gapic_v1.method.DEFAULT,
         metadata=None,
     ):
         """Deletes a long-running operation.
@@ -311,6 +349,8 @@ def delete_operation(
                 unspecified, the the default timeout in the client
                 configuration is used. If ``None``, then the RPC method will
                 not time out.
+            compression (grpc.Compression): An element of grpc.compression
+                e.g. grpc.compression.Gzip.
             metadata (Optional[List[Tuple[str, str]]]): Additional gRPC
                 metadata.
 
@@ -329,4 +369,10 @@ def delete_operation(
         metadata = metadata or []
         metadata.append(gapic_v1.routing_header.to_grpc_metadata({"name": name}))
 
-        self._delete_operation(request, retry=retry, timeout=timeout, metadata=metadata)
+        self._delete_operation(
+            request,
+            retry=retry,
+            timeout=timeout,
+            compression=compression,
+            metadata=metadata,
+        )
diff --git a/google/api_core/operations_v1/operations_client_config.py b/google/api_core/operations_v1/operations_client_config.py
index 6cf95753..3ad3548c 100644
--- a/google/api_core/operations_v1/operations_client_config.py
+++ b/google/api_core/operations_v1/operations_client_config.py
@@ -12,8 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-"""gapic configuration for the googe.longrunning.operations client."""
+"""gapic configuration for the google.longrunning.operations client."""
 
+# DEPRECATED: retry and timeout classes are instantiated directly
 config = {
     "interfaces": {
         "google.longrunning.Operations": {
diff --git a/google/api_core/operations_v1/operations_rest_client_async.py b/google/api_core/operations_v1/operations_rest_client_async.py
new file mode 100644
index 00000000..7ab0cd36
--- /dev/null
+++ b/google/api_core/operations_v1/operations_rest_client_async.py
@@ -0,0 +1,345 @@
+# -*- coding: utf-8 -*-
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+from typing import Optional, Sequence, Tuple, Union
+
+from google.api_core import client_options as client_options_lib  # type: ignore
+from google.api_core import gapic_v1  # type: ignore
+from google.api_core.operations_v1 import pagers_async as pagers
+from google.api_core.operations_v1.transports.base import (
+    DEFAULT_CLIENT_INFO,
+    OperationsTransport,
+)
+from google.api_core.operations_v1.abstract_operations_base_client import (
+    AbstractOperationsBaseClient,
+)
+from google.longrunning import operations_pb2
+
+try:
+    from google.auth.aio import credentials as ga_credentials  # type: ignore
+except ImportError as e:  # pragma: NO COVER
+    raise ImportError(
+        "The `async_rest` extra of `google-api-core` is required to use long-running operations.  Install it by running "
+        "`pip install google-api-core[async_rest]`."
+    ) from e
+
+
+class AsyncOperationsRestClient(AbstractOperationsBaseClient):
+    """Manages long-running operations with a REST API service for the asynchronous client.
+
+    When an API method normally takes long time to complete, it can be
+    designed to return [Operation][google.api_core.operations_v1.Operation] to the
+    client, and the client can use this interface to receive the real
+    response asynchronously by polling the operation resource, or pass
+    the operation resource to another API (such as Google Cloud Pub/Sub
+    API) to receive the response. Any API service that returns
+    long-running operations should implement the ``Operations``
+    interface so developers can have a consistent client experience.
+    """
+
+    def __init__(
+        self,
+        *,
+        credentials: Optional[ga_credentials.Credentials] = None,
+        transport: Union[str, OperationsTransport, None] = None,
+        client_options: Optional[client_options_lib.ClientOptions] = None,
+        client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+    ) -> None:
+        """Instantiates the operations client.
+
+        Args:
+            credentials (Optional[google.auth.aio.credentials.Credentials]): The
+                authorization credentials to attach to requests. These
+                credentials identify the application to the service; if none
+                are specified, the client will attempt to ascertain the
+                credentials from the environment.
+            transport (Union[str, OperationsTransport]): The
+                transport to use. If set to None, this defaults to 'rest_asyncio'.
+            client_options (google.api_core.client_options.ClientOptions): Custom options for the
+                client. It won't take effect if a ``transport`` instance is provided.
+                (1) The ``api_endpoint`` property can be used to override the
+                default endpoint provided by the client. GOOGLE_API_USE_MTLS_ENDPOINT
+                environment variable can also be used to override the endpoint:
+                "always" (always use the default mTLS endpoint), "never" (always
+                use the default regular endpoint) and "auto" (auto switch to the
+                default mTLS endpoint if client certificate is present, this is
+                the default value). However, the ``api_endpoint`` property takes
+                precedence if provided.
+                (2) If GOOGLE_API_USE_CLIENT_CERTIFICATE environment variable
+                is "true", then the ``client_cert_source`` property can be used
+                to provide client certificate for mutual TLS transport. If
+                not provided, the default SSL client certificate will be used if
+                present. If GOOGLE_API_USE_CLIENT_CERTIFICATE is "false" or not
+                set, no client certificate will be used.
+            client_info (google.api_core.gapic_v1.client_info.ClientInfo):
+                The client info used to send a user-agent string along with
+                API requests. If ``None``, then default info will be used.
+                Generally, you only need to set this if you're developing
+                your own client library.
+
+        Raises:
+            google.auth.exceptions.MutualTLSChannelError: If mutual TLS transport
+                creation failed for any reason.
+        """
+        super().__init__(
+            credentials=credentials,  # type: ignore
+            # NOTE: If a transport is not provided, we force the client to use the async
+            # REST transport.
+            transport=transport or "rest_asyncio",
+            client_options=client_options,
+            client_info=client_info,
+        )
+
+    async def get_operation(
+        self,
+        name: str,
+        *,
+        # TODO(https://github.com/googleapis/python-api-core/issues/722): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry=gapic_v1.method_async.DEFAULT,
+        timeout: Optional[float] = None,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> operations_pb2.Operation:
+        r"""Gets the latest state of a long-running operation.
+        Clients can use this method to poll the operation result
+        at intervals as recommended by the API service.
+
+        Args:
+            name (str):
+                The name of the operation resource.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+
+        Returns:
+            google.longrunning.operations_pb2.Operation:
+                This resource represents a long-
+                running operation that is the result of a
+                network API call.
+
+        """
+
+        request = operations_pb2.GetOperationRequest(name=name)
+
+        # Wrap the RPC method; this adds retry and timeout information,
+        # and friendly error handling.
+        rpc = self._transport._wrapped_methods[self._transport.get_operation]
+
+        # Certain fields should be provided within the metadata header;
+        # add these here.
+        metadata = tuple(metadata or ()) + (
+            gapic_v1.routing_header.to_grpc_metadata((("name", request.name),)),
+        )
+
+        # Send the request.
+        response = await rpc(
+            request,
+            retry=retry,
+            timeout=timeout,
+            metadata=metadata,
+        )
+
+        # Done; return the response.
+        return response
+
+    async def list_operations(
+        self,
+        name: str,
+        filter_: Optional[str] = None,
+        *,
+        page_size: Optional[int] = None,
+        page_token: Optional[str] = None,
+        # TODO(https://github.com/googleapis/python-api-core/issues/722): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry=gapic_v1.method_async.DEFAULT,
+        timeout: Optional[float] = None,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> pagers.ListOperationsAsyncPager:
+        r"""Lists operations that match the specified filter in the request.
+        If the server doesn't support this method, it returns
+        ``UNIMPLEMENTED``.
+
+        NOTE: the ``name`` binding allows API services to override the
+        binding to use different resource name schemes, such as
+        ``users/*/operations``. To override the binding, API services
+        can add a binding such as ``"/v1/{name=users/*}/operations"`` to
+        their service configuration. For backwards compatibility, the
+        default name includes the operations collection id, however
+        overriding users must ensure the name binding is the parent
+        resource, without the operations collection id.
+
+        Args:
+            name (str):
+                The name of the operation's parent
+                resource.
+            filter_ (str):
+                The standard list filter.
+                This corresponds to the ``filter`` field
+                on the ``request`` instance; if ``request`` is provided, this
+                should not be set.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+
+        Returns:
+            google.api_core.operations_v1.pagers.ListOperationsPager:
+                The response message for
+                [Operations.ListOperations][google.api_core.operations_v1.Operations.ListOperations].
+
+                Iterating over this object will yield results and
+                resolve additional pages automatically.
+
+        """
+        # Create a protobuf request object.
+        request = operations_pb2.ListOperationsRequest(name=name, filter=filter_)
+        if page_size is not None:
+            request.page_size = page_size
+        if page_token is not None:
+            request.page_token = page_token
+
+        # Wrap the RPC method; this adds retry and timeout information,
+        # and friendly error handling.
+        rpc = self._transport._wrapped_methods[self._transport.list_operations]
+
+        # Certain fields should be provided within the metadata header;
+        # add these here.
+        metadata = tuple(metadata or ()) + (
+            gapic_v1.routing_header.to_grpc_metadata((("name", request.name),)),
+        )
+
+        # Send the request.
+        response = await rpc(
+            request,
+            retry=retry,
+            timeout=timeout,
+            metadata=metadata,
+        )
+
+        # This method is paged; wrap the response in a pager, which provides
+        # an `__iter__` convenience method.
+        response = pagers.ListOperationsAsyncPager(
+            method=rpc,
+            request=request,
+            response=response,
+            metadata=metadata,
+        )
+
+        # Done; return the response.
+        return response
+
+    async def delete_operation(
+        self,
+        name: str,
+        *,
+        # TODO(https://github.com/googleapis/python-api-core/issues/722): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry=gapic_v1.method_async.DEFAULT,
+        timeout: Optional[float] = None,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> None:
+        r"""Deletes a long-running operation. This method indicates that the
+        client is no longer interested in the operation result. It does
+        not cancel the operation. If the server doesn't support this
+        method, it returns ``google.rpc.Code.UNIMPLEMENTED``.
+
+        Args:
+            name (str):
+                The name of the operation resource to
+                be deleted.
+
+                This corresponds to the ``name`` field
+                on the ``request`` instance; if ``request`` is provided, this
+                should not be set.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+        """
+        # Create the request object.
+        request = operations_pb2.DeleteOperationRequest(name=name)
+
+        # Wrap the RPC method; this adds retry and timeout information,
+        # and friendly error handling.
+        rpc = self._transport._wrapped_methods[self._transport.delete_operation]
+
+        # Certain fields should be provided within the metadata header;
+        # add these here.
+        metadata = tuple(metadata or ()) + (
+            gapic_v1.routing_header.to_grpc_metadata((("name", request.name),)),
+        )
+
+        # Send the request.
+        await rpc(
+            request,
+            retry=retry,
+            timeout=timeout,
+            metadata=metadata,
+        )
+
+    async def cancel_operation(
+        self,
+        name: Optional[str] = None,
+        *,
+        # TODO(https://github.com/googleapis/python-api-core/issues/722): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry=gapic_v1.method_async.DEFAULT,
+        timeout: Optional[float] = None,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> None:
+        r"""Starts asynchronous cancellation on a long-running operation.
+        The server makes a best effort to cancel the operation, but
+        success is not guaranteed. If the server doesn't support this
+        method, it returns ``google.rpc.Code.UNIMPLEMENTED``. Clients
+        can use
+        [Operations.GetOperation][google.api_core.operations_v1.Operations.GetOperation]
+        or other methods to check whether the cancellation succeeded or
+        whether the operation completed despite cancellation. On
+        successful cancellation, the operation is not deleted; instead,
+        it becomes an operation with an
+        [Operation.error][google.api_core.operations_v1.Operation.error] value with
+        a [google.rpc.Status.code][google.rpc.Status.code] of 1,
+        corresponding to ``Code.CANCELLED``.
+
+        Args:
+            name (str):
+                The name of the operation resource to
+                be cancelled.
+
+                This corresponds to the ``name`` field
+                on the ``request`` instance; if ``request`` is provided, this
+                should not be set.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+        """
+        # Create the request object.
+        request = operations_pb2.CancelOperationRequest(name=name)
+
+        # Wrap the RPC method; this adds retry and timeout information,
+        # and friendly error handling.
+        rpc = self._transport._wrapped_methods[self._transport.cancel_operation]
+
+        # Certain fields should be provided within the metadata header;
+        # add these here.
+        metadata = tuple(metadata or ()) + (
+            gapic_v1.routing_header.to_grpc_metadata((("name", request.name),)),
+        )
+
+        # Send the request.
+        await rpc(
+            request,
+            retry=retry,
+            timeout=timeout,
+            metadata=metadata,
+        )
diff --git a/google/api_core/operations_v1/pagers.py b/google/api_core/operations_v1/pagers.py
new file mode 100644
index 00000000..132f1c66
--- /dev/null
+++ b/google/api_core/operations_v1/pagers.py
@@ -0,0 +1,67 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+from typing import (
+    Callable,
+    Iterator,
+    Sequence,
+    Tuple,
+)
+
+from google.longrunning import operations_pb2
+from google.api_core.operations_v1.pagers_base import ListOperationsPagerBase
+
+
+class ListOperationsPager(ListOperationsPagerBase):
+    """A pager for iterating through ``list_operations`` requests.
+
+    This class thinly wraps an initial
+    :class:`google.longrunning.operations_pb2.ListOperationsResponse` object, and
+    provides an ``__iter__`` method to iterate through its
+    ``operations`` field.
+
+    If there are more pages, the ``__iter__`` method will make additional
+    ``ListOperations`` requests and continue to iterate
+    through the ``operations`` field on the
+    corresponding responses.
+
+    All the usual :class:`google.longrunning.operations_pb2.ListOperationsResponse`
+    attributes are available on the pager. If multiple requests are made, only
+    the most recent response is retained, and thus used for attribute lookup.
+    """
+
+    def __init__(
+        self,
+        method: Callable[..., operations_pb2.ListOperationsResponse],
+        request: operations_pb2.ListOperationsRequest,
+        response: operations_pb2.ListOperationsResponse,
+        *,
+        metadata: Sequence[Tuple[str, str]] = ()
+    ):
+        super().__init__(
+            method=method, request=request, response=response, metadata=metadata
+        )
+
+    @property
+    def pages(self) -> Iterator[operations_pb2.ListOperationsResponse]:
+        yield self._response
+        while self._response.next_page_token:
+            self._request.page_token = self._response.next_page_token
+            self._response = self._method(self._request, metadata=self._metadata)
+            yield self._response
+
+    def __iter__(self) -> Iterator[operations_pb2.Operation]:
+        for page in self.pages:
+            yield from page.operations
diff --git a/google/api_core/operations_v1/pagers_async.py b/google/api_core/operations_v1/pagers_async.py
new file mode 100644
index 00000000..e2909dd5
--- /dev/null
+++ b/google/api_core/operations_v1/pagers_async.py
@@ -0,0 +1,71 @@
+# -*- coding: utf-8 -*-
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+from typing import (
+    Callable,
+    AsyncIterator,
+    Sequence,
+    Tuple,
+)
+
+from google.longrunning import operations_pb2
+from google.api_core.operations_v1.pagers_base import ListOperationsPagerBase
+
+
+class ListOperationsAsyncPager(ListOperationsPagerBase):
+    """A pager for iterating through ``list_operations`` requests.
+
+    This class thinly wraps an initial
+    :class:`google.longrunning.operations_pb2.ListOperationsResponse` object, and
+    provides an ``__iter__`` method to iterate through its
+    ``operations`` field.
+
+    If there are more pages, the ``__iter__`` method will make additional
+    ``ListOperations`` requests and continue to iterate
+    through the ``operations`` field on the
+    corresponding responses.
+
+    All the usual :class:`google.longrunning.operations_pb2.ListOperationsResponse`
+    attributes are available on the pager. If multiple requests are made, only
+    the most recent response is retained, and thus used for attribute lookup.
+    """
+
+    def __init__(
+        self,
+        method: Callable[..., operations_pb2.ListOperationsResponse],
+        request: operations_pb2.ListOperationsRequest,
+        response: operations_pb2.ListOperationsResponse,
+        *,
+        metadata: Sequence[Tuple[str, str]] = ()
+    ):
+        super().__init__(
+            method=method, request=request, response=response, metadata=metadata
+        )
+
+    @property
+    async def pages(self) -> AsyncIterator[operations_pb2.ListOperationsResponse]:
+        yield self._response
+        while self._response.next_page_token:
+            self._request.page_token = self._response.next_page_token
+            self._response = await self._method(self._request, metadata=self._metadata)
+            yield self._response
+
+    def __aiter__(self) -> AsyncIterator[operations_pb2.Operation]:
+        async def async_generator():
+            async for page in self.pages:
+                for operation in page.operations:
+                    yield operation
+
+        return async_generator()
diff --git a/google/api_core/operations_v1/pagers_base.py b/google/api_core/operations_v1/pagers_base.py
new file mode 100644
index 00000000..24caf74f
--- /dev/null
+++ b/google/api_core/operations_v1/pagers_base.py
@@ -0,0 +1,73 @@
+# -*- coding: utf-8 -*-
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+from typing import (
+    Any,
+    Callable,
+    Sequence,
+    Tuple,
+)
+
+from google.longrunning import operations_pb2
+
+
+class ListOperationsPagerBase:
+    """A pager for iterating through ``list_operations`` requests.
+
+    This class thinly wraps an initial
+    :class:`google.longrunning.operations_pb2.ListOperationsResponse` object, and
+    provides an ``__iter__`` method to iterate through its
+    ``operations`` field.
+
+    If there are more pages, the ``__iter__`` method will make additional
+    ``ListOperations`` requests and continue to iterate
+    through the ``operations`` field on the
+    corresponding responses.
+
+    All the usual :class:`google.longrunning.operations_pb2.ListOperationsResponse`
+    attributes are available on the pager. If multiple requests are made, only
+    the most recent response is retained, and thus used for attribute lookup.
+    """
+
+    def __init__(
+        self,
+        method: Callable[..., operations_pb2.ListOperationsResponse],
+        request: operations_pb2.ListOperationsRequest,
+        response: operations_pb2.ListOperationsResponse,
+        *,
+        metadata: Sequence[Tuple[str, str]] = ()
+    ):
+        """Instantiate the pager.
+
+        Args:
+            method (Callable): The method that was originally called, and
+                which instantiated this pager.
+            request (google.longrunning.operations_pb2.ListOperationsRequest):
+                The initial request object.
+            response (google.longrunning.operations_pb2.ListOperationsResponse):
+                The initial response object.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+        """
+        self._method = method
+        self._request = request
+        self._response = response
+        self._metadata = metadata
+
+    def __getattr__(self, name: str) -> Any:
+        return getattr(self._response, name)
+
+    def __repr__(self) -> str:
+        return "{0}<{1!r}>".format(self.__class__.__name__, self._response)
diff --git a/google/api_core/operations_v1/transports/__init__.py b/google/api_core/operations_v1/transports/__init__.py
new file mode 100644
index 00000000..8c24ce6e
--- /dev/null
+++ b/google/api_core/operations_v1/transports/__init__.py
@@ -0,0 +1,39 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+from collections import OrderedDict
+from typing import cast, Dict, Tuple
+
+from .base import OperationsTransport
+from .rest import OperationsRestTransport
+
+# Compile a registry of transports.
+_transport_registry: Dict[str, OperationsTransport] = OrderedDict()
+_transport_registry["rest"] = cast(OperationsTransport, OperationsRestTransport)
+
+__all__: Tuple[str, ...] = ("OperationsTransport", "OperationsRestTransport")
+
+try:
+    from .rest_asyncio import AsyncOperationsRestTransport
+
+    __all__ += ("AsyncOperationsRestTransport",)
+    _transport_registry["rest_asyncio"] = cast(
+        OperationsTransport, AsyncOperationsRestTransport
+    )
+except ImportError:
+    # This import requires the `async_rest` extra.
+    # Don't raise an exception if `AsyncOperationsRestTransport` cannot be imported
+    # as other transports are still available.
+    pass
diff --git a/google/api_core/operations_v1/transports/base.py b/google/api_core/operations_v1/transports/base.py
new file mode 100644
index 00000000..71764c1e
--- /dev/null
+++ b/google/api_core/operations_v1/transports/base.py
@@ -0,0 +1,294 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+import abc
+import re
+from typing import Awaitable, Callable, Optional, Sequence, Union
+
+import google.api_core  # type: ignore
+from google.api_core import exceptions as core_exceptions  # type: ignore
+from google.api_core import gapic_v1  # type: ignore
+from google.api_core import retry as retries  # type: ignore
+from google.api_core import version
+import google.auth  # type: ignore
+from google.auth import credentials as ga_credentials  # type: ignore
+from google.longrunning import operations_pb2
+from google.oauth2 import service_account  # type: ignore
+import google.protobuf
+from google.protobuf import empty_pb2, json_format  # type: ignore
+from grpc import Compression
+
+
+PROTOBUF_VERSION = google.protobuf.__version__
+
+DEFAULT_CLIENT_INFO = gapic_v1.client_info.ClientInfo(
+    gapic_version=version.__version__,
+)
+
+
+class OperationsTransport(abc.ABC):
+    """Abstract transport class for Operations."""
+
+    AUTH_SCOPES = ()
+
+    DEFAULT_HOST: str = "longrunning.googleapis.com"
+
+    def __init__(
+        self,
+        *,
+        host: str = DEFAULT_HOST,
+        # TODO(https://github.com/googleapis/python-api-core/issues/709): update type hint for credentials to include `google.auth.aio.Credentials`.
+        credentials: Optional[ga_credentials.Credentials] = None,
+        credentials_file: Optional[str] = None,
+        scopes: Optional[Sequence[str]] = None,
+        quota_project_id: Optional[str] = None,
+        client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
+        url_scheme="https",
+        **kwargs,
+    ) -> None:
+        """Instantiate the transport.
+
+        Args:
+            host (Optional[str]):
+                 The hostname to connect to.
+            credentials (Optional[google.auth.credentials.Credentials]): The
+                authorization credentials to attach to requests. These
+                credentials identify the application to the service; if none
+                are specified, the client will attempt to ascertain the
+                credentials from the environment.
+            credentials_file (Optional[str]): A file with credentials that can
+                be loaded with :func:`google.auth.load_credentials_from_file`.
+                This argument is mutually exclusive with credentials.
+
+                .. warning::
+                    Important: If you accept a credential configuration (credential JSON/File/Stream)
+                    from an external source for authentication to Google Cloud Platform, you must
+                    validate it before providing it to any Google API or client library. Providing an
+                    unvalidated credential configuration to Google APIs or libraries can compromise
+                    the security of your systems and data. For more information, refer to
+                    `Validate credential configurations from external sources`_.
+
+                .. _Validate credential configurations from external sources:
+
+                https://cloud.google.com/docs/authentication/external/externally-sourced-credentials
+            scopes (Optional[Sequence[str]]): A list of scopes.
+            quota_project_id (Optional[str]): An optional project to use for billing
+                and quota.
+            client_info (google.api_core.gapic_v1.client_info.ClientInfo):
+                The client info used to send a user-agent string along with
+                API requests. If ``None``, then default info will be used.
+                Generally, you only need to set this if you're developing
+                your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
+            url_scheme: the protocol scheme for the API endpoint.  Normally
+                "https", but for testing or local servers,
+                "http" can be specified.
+        """
+        maybe_url_match = re.match("^(?P<scheme>http(?:s)?://)?(?P<host>.*)$", host)
+        if maybe_url_match is None:
+            raise ValueError(
+                f"Unexpected hostname structure: {host}"
+            )  # pragma: NO COVER
+
+        url_match_items = maybe_url_match.groupdict()
+
+        host = f"{url_scheme}://{host}" if not url_match_items["scheme"] else host
+
+        # Save the hostname. Default to port 443 (HTTPS) if none is specified.
+        if ":" not in host:
+            host += ":443"  # pragma: NO COVER
+        self._host = host
+
+        scopes_kwargs = {"scopes": scopes, "default_scopes": self.AUTH_SCOPES}
+
+        # Save the scopes.
+        self._scopes = scopes
+
+        # If no credentials are provided, then determine the appropriate
+        # defaults.
+        if credentials and credentials_file:
+            raise core_exceptions.DuplicateCredentialArgs(
+                "'credentials_file' and 'credentials' are mutually exclusive"
+            )
+
+        if credentials_file is not None:
+            credentials, _ = google.auth.load_credentials_from_file(
+                credentials_file, **scopes_kwargs, quota_project_id=quota_project_id
+            )
+
+        elif credentials is None:
+            credentials, _ = google.auth.default(
+                **scopes_kwargs, quota_project_id=quota_project_id
+            )
+
+        # If the credentials are service account credentials, then always try to use self signed JWT.
+        if (
+            always_use_jwt_access
+            and isinstance(credentials, service_account.Credentials)
+            and hasattr(service_account.Credentials, "with_always_use_jwt_access")
+        ):
+            credentials = credentials.with_always_use_jwt_access(True)
+
+        # Save the credentials.
+        self._credentials = credentials
+
+    def _prep_wrapped_messages(self, client_info):
+        # Precompute the wrapped methods.
+        self._wrapped_methods = {
+            self.list_operations: gapic_v1.method.wrap_method(
+                self.list_operations,
+                default_retry=retries.Retry(
+                    initial=0.5,
+                    maximum=10.0,
+                    multiplier=2.0,
+                    predicate=retries.if_exception_type(
+                        core_exceptions.ServiceUnavailable,
+                    ),
+                    deadline=10.0,
+                ),
+                default_timeout=10.0,
+                default_compression=Compression.NoCompression,
+                client_info=client_info,
+            ),
+            self.get_operation: gapic_v1.method.wrap_method(
+                self.get_operation,
+                default_retry=retries.Retry(
+                    initial=0.5,
+                    maximum=10.0,
+                    multiplier=2.0,
+                    predicate=retries.if_exception_type(
+                        core_exceptions.ServiceUnavailable,
+                    ),
+                    deadline=10.0,
+                ),
+                default_timeout=10.0,
+                default_compression=Compression.NoCompression,
+                client_info=client_info,
+            ),
+            self.delete_operation: gapic_v1.method.wrap_method(
+                self.delete_operation,
+                default_retry=retries.Retry(
+                    initial=0.5,
+                    maximum=10.0,
+                    multiplier=2.0,
+                    predicate=retries.if_exception_type(
+                        core_exceptions.ServiceUnavailable,
+                    ),
+                    deadline=10.0,
+                ),
+                default_timeout=10.0,
+                default_compression=Compression.NoCompression,
+                client_info=client_info,
+            ),
+            self.cancel_operation: gapic_v1.method.wrap_method(
+                self.cancel_operation,
+                default_retry=retries.Retry(
+                    initial=0.5,
+                    maximum=10.0,
+                    multiplier=2.0,
+                    predicate=retries.if_exception_type(
+                        core_exceptions.ServiceUnavailable,
+                    ),
+                    deadline=10.0,
+                ),
+                default_timeout=10.0,
+                default_compression=Compression.NoCompression,
+                client_info=client_info,
+            ),
+        }
+
+    def close(self):
+        """Closes resources associated with the transport.
+
+        .. warning::
+             Only call this method if the transport is NOT shared
+             with other clients - this may cause errors in other clients!
+        """
+        raise NotImplementedError()
+
+    def _convert_protobuf_message_to_dict(
+        self, message: google.protobuf.message.Message
+    ):
+        r"""Converts protobuf message to a dictionary.
+
+        When the dictionary is encoded to JSON, it conforms to proto3 JSON spec.
+
+        Args:
+            message(google.protobuf.message.Message): The protocol buffers message
+                instance to serialize.
+
+        Returns:
+            A dict representation of the protocol buffer message.
+        """
+        # TODO(https://github.com/googleapis/python-api-core/issues/643): For backwards compatibility
+        # with protobuf 3.x 4.x, Remove once support for protobuf 3.x and 4.x is dropped.
+        if PROTOBUF_VERSION[0:2] in ["3.", "4."]:
+            result = json_format.MessageToDict(
+                message,
+                preserving_proto_field_name=True,
+                including_default_value_fields=True,  # type: ignore # backward compatibility
+            )
+        else:
+            result = json_format.MessageToDict(
+                message,
+                preserving_proto_field_name=True,
+                always_print_fields_with_no_presence=True,
+            )
+
+        return result
+
+    @property
+    def list_operations(
+        self,
+    ) -> Callable[
+        [operations_pb2.ListOperationsRequest],
+        Union[
+            operations_pb2.ListOperationsResponse,
+            Awaitable[operations_pb2.ListOperationsResponse],
+        ],
+    ]:
+        raise NotImplementedError()
+
+    @property
+    def get_operation(
+        self,
+    ) -> Callable[
+        [operations_pb2.GetOperationRequest],
+        Union[operations_pb2.Operation, Awaitable[operations_pb2.Operation]],
+    ]:
+        raise NotImplementedError()
+
+    @property
+    def delete_operation(
+        self,
+    ) -> Callable[
+        [operations_pb2.DeleteOperationRequest],
+        Union[empty_pb2.Empty, Awaitable[empty_pb2.Empty]],
+    ]:
+        raise NotImplementedError()
+
+    @property
+    def cancel_operation(
+        self,
+    ) -> Callable[
+        [operations_pb2.CancelOperationRequest],
+        Union[empty_pb2.Empty, Awaitable[empty_pb2.Empty]],
+    ]:
+        raise NotImplementedError()
+
+
+__all__ = ("OperationsTransport",)
diff --git a/google/api_core/operations_v1/transports/rest.py b/google/api_core/operations_v1/transports/rest.py
new file mode 100644
index 00000000..0705c518
--- /dev/null
+++ b/google/api_core/operations_v1/transports/rest.py
@@ -0,0 +1,485 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+from typing import Callable, Dict, Optional, Sequence, Tuple, Union
+
+from requests import __version__ as requests_version
+
+from google.api_core import exceptions as core_exceptions  # type: ignore
+from google.api_core import gapic_v1  # type: ignore
+from google.api_core import path_template  # type: ignore
+from google.api_core import rest_helpers  # type: ignore
+from google.api_core import retry as retries  # type: ignore
+from google.auth import credentials as ga_credentials  # type: ignore
+from google.auth.transport.requests import AuthorizedSession  # type: ignore
+from google.longrunning import operations_pb2  # type: ignore
+from google.protobuf import empty_pb2  # type: ignore
+from google.protobuf import json_format  # type: ignore
+import google.protobuf
+
+import grpc
+from .base import DEFAULT_CLIENT_INFO as BASE_DEFAULT_CLIENT_INFO, OperationsTransport
+
+PROTOBUF_VERSION = google.protobuf.__version__
+
+OptionalRetry = Union[retries.Retry, object]
+
+DEFAULT_CLIENT_INFO = gapic_v1.client_info.ClientInfo(
+    gapic_version=BASE_DEFAULT_CLIENT_INFO.gapic_version,
+    grpc_version=None,
+    rest_version=f"requests@{requests_version}",
+)
+
+
+class OperationsRestTransport(OperationsTransport):
+    """REST backend transport for Operations.
+
+    Manages long-running operations with an API service.
+
+    When an API method normally takes long time to complete, it can be
+    designed to return [Operation][google.api_core.operations_v1.Operation] to the
+    client, and the client can use this interface to receive the real
+    response asynchronously by polling the operation resource, or pass
+    the operation resource to another API (such as Google Cloud Pub/Sub
+    API) to receive the response. Any API service that returns
+    long-running operations should implement the ``Operations``
+    interface so developers can have a consistent client experience.
+
+    This class defines the same methods as the primary client, so the
+    primary client can load the underlying transport implementation
+    and call it.
+
+    It sends JSON representations of protocol buffers over HTTP/1.1
+    """
+
+    def __init__(
+        self,
+        *,
+        host: str = "longrunning.googleapis.com",
+        credentials: Optional[ga_credentials.Credentials] = None,
+        credentials_file: Optional[str] = None,
+        scopes: Optional[Sequence[str]] = None,
+        client_cert_source_for_mtls: Optional[Callable[[], Tuple[bytes, bytes]]] = None,
+        quota_project_id: Optional[str] = None,
+        client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
+        url_scheme: str = "https",
+        http_options: Optional[Dict] = None,
+        path_prefix: str = "v1",
+    ) -> None:
+        """Instantiate the transport.
+
+        Args:
+            host (Optional[str]):
+                 The hostname to connect to.
+            credentials (Optional[google.auth.credentials.Credentials]): The
+                authorization credentials to attach to requests. These
+                credentials identify the application to the service; if none
+                are specified, the client will attempt to ascertain the
+                credentials from the environment.
+
+            credentials_file (Optional[str]): A file with credentials that can
+                be loaded with :func:`google.auth.load_credentials_from_file`.
+                This argument is ignored if ``channel`` is provided.
+
+                .. warning::
+                    Important: If you accept a credential configuration (credential JSON/File/Stream)
+                    from an external source for authentication to Google Cloud Platform, you must
+                    validate it before providing it to any Google API or client library. Providing an
+                    unvalidated credential configuration to Google APIs or libraries can compromise
+                    the security of your systems and data. For more information, refer to
+                    `Validate credential configurations from external sources`_.
+
+                .. _Validate credential configurations from external sources:
+
+                https://cloud.google.com/docs/authentication/external/externally-sourced-credentials
+            scopes (Optional(Sequence[str])): A list of scopes. This argument is
+                ignored if ``channel`` is provided.
+            client_cert_source_for_mtls (Callable[[], Tuple[bytes, bytes]]): Client
+                certificate to configure mutual TLS HTTP channel. It is ignored
+                if ``channel`` is provided.
+            quota_project_id (Optional[str]): An optional project to use for billing
+                and quota.
+            client_info (google.api_core.gapic_v1.client_info.ClientInfo):
+                The client info used to send a user-agent string along with
+                API requests. If ``None``, then default info will be used.
+                Generally, you only need to set this if you're developing
+                your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
+            url_scheme: the protocol scheme for the API endpoint.  Normally
+                "https", but for testing or local servers,
+                "http" can be specified.
+            http_options: a dictionary of http_options for transcoding, to override
+                the defaults from operations.proto.  Each method has an entry
+                with the corresponding http rules as value.
+            path_prefix: path prefix (usually represents API version). Set to
+                "v1" by default.
+
+        """
+        # Run the base constructor
+        # TODO(yon-mg): resolve other ctor params i.e. scopes, quota, etc.
+        # TODO: When custom host (api_endpoint) is set, `scopes` must *also* be set on the
+        # credentials object
+        super().__init__(
+            host=host,
+            credentials=credentials,
+            client_info=client_info,
+            always_use_jwt_access=always_use_jwt_access,
+        )
+        self._session = AuthorizedSession(
+            self._credentials, default_host=self.DEFAULT_HOST
+        )
+        if client_cert_source_for_mtls:
+            self._session.configure_mtls_channel(client_cert_source_for_mtls)
+        # TODO(https://github.com/googleapis/python-api-core/issues/720): Add wrap logic directly to the property methods for callables.
+        self._prep_wrapped_messages(client_info)
+        self._http_options = http_options or {}
+        self._path_prefix = path_prefix
+
+    def _list_operations(
+        self,
+        request: operations_pb2.ListOperationsRequest,
+        *,
+        # TODO(https://github.com/googleapis/python-api-core/issues/723): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
+        timeout: Optional[float] = None,
+        compression: Optional[grpc.Compression] = gapic_v1.method.DEFAULT,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> operations_pb2.ListOperationsResponse:
+        r"""Call the list operations method over HTTP.
+
+        Args:
+            request (~.operations_pb2.ListOperationsRequest):
+                The request object. The request message for
+                [Operations.ListOperations][google.api_core.operations_v1.Operations.ListOperations].
+
+            retry (google.api_core.retry.Retry): Designation of what errors, if any,
+                should be retried.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+
+        Returns:
+            ~.operations_pb2.ListOperationsResponse:
+                The response message for
+                [Operations.ListOperations][google.api_core.operations_v1.Operations.ListOperations].
+
+        """
+
+        http_options = [
+            {
+                "method": "get",
+                "uri": "/{}/{{name=**}}/operations".format(self._path_prefix),
+            },
+        ]
+        if "google.longrunning.Operations.ListOperations" in self._http_options:
+            http_options = self._http_options[
+                "google.longrunning.Operations.ListOperations"
+            ]
+
+        request_kwargs = self._convert_protobuf_message_to_dict(request)
+        transcoded_request = path_template.transcode(http_options, **request_kwargs)
+
+        uri = transcoded_request["uri"]
+        method = transcoded_request["method"]
+
+        # Jsonify the query params
+        query_params_request = operations_pb2.ListOperationsRequest()
+        json_format.ParseDict(transcoded_request["query_params"], query_params_request)
+        query_params = json_format.MessageToDict(
+            query_params_request,
+            preserving_proto_field_name=False,
+            use_integers_for_enums=False,
+        )
+
+        # Send the request
+        headers = dict(metadata)
+        headers["Content-Type"] = "application/json"
+        # TODO(https://github.com/googleapis/python-api-core/issues/721): Update incorrect use of `uri`` variable name.
+        response = getattr(self._session, method)(
+            "{host}{uri}".format(host=self._host, uri=uri),
+            timeout=timeout,
+            headers=headers,
+            params=rest_helpers.flatten_query_params(query_params),
+        )
+
+        # In case of error, raise the appropriate core_exceptions.GoogleAPICallError exception
+        # subclass.
+        if response.status_code >= 400:
+            raise core_exceptions.from_http_response(response)
+
+        # Return the response
+        api_response = operations_pb2.ListOperationsResponse()
+        json_format.Parse(response.content, api_response, ignore_unknown_fields=False)
+        return api_response
+
+    def _get_operation(
+        self,
+        request: operations_pb2.GetOperationRequest,
+        *,
+        # TODO(https://github.com/googleapis/python-api-core/issues/723): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
+        timeout: Optional[float] = None,
+        compression: Optional[grpc.Compression] = gapic_v1.method.DEFAULT,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> operations_pb2.Operation:
+        r"""Call the get operation method over HTTP.
+
+        Args:
+            request (~.operations_pb2.GetOperationRequest):
+                The request object. The request message for
+                [Operations.GetOperation][google.api_core.operations_v1.Operations.GetOperation].
+
+            retry (google.api_core.retry.Retry): Designation of what errors, if any,
+                should be retried.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+
+        Returns:
+            ~.operations_pb2.Operation:
+                This resource represents a long-
+                running operation that is the result of a
+                network API call.
+
+        """
+
+        http_options = [
+            {
+                "method": "get",
+                "uri": "/{}/{{name=**/operations/*}}".format(self._path_prefix),
+            },
+        ]
+        if "google.longrunning.Operations.GetOperation" in self._http_options:
+            http_options = self._http_options[
+                "google.longrunning.Operations.GetOperation"
+            ]
+
+        request_kwargs = self._convert_protobuf_message_to_dict(request)
+        transcoded_request = path_template.transcode(http_options, **request_kwargs)
+
+        uri = transcoded_request["uri"]
+        method = transcoded_request["method"]
+
+        # Jsonify the query params
+        query_params_request = operations_pb2.GetOperationRequest()
+        json_format.ParseDict(transcoded_request["query_params"], query_params_request)
+        query_params = json_format.MessageToDict(
+            query_params_request,
+            preserving_proto_field_name=False,
+            use_integers_for_enums=False,
+        )
+
+        # Send the request
+        headers = dict(metadata)
+        headers["Content-Type"] = "application/json"
+        # TODO(https://github.com/googleapis/python-api-core/issues/721): Update incorrect use of `uri`` variable name.
+        response = getattr(self._session, method)(
+            "{host}{uri}".format(host=self._host, uri=uri),
+            timeout=timeout,
+            headers=headers,
+            params=rest_helpers.flatten_query_params(query_params),
+        )
+
+        # In case of error, raise the appropriate core_exceptions.GoogleAPICallError exception
+        # subclass.
+        if response.status_code >= 400:
+            raise core_exceptions.from_http_response(response)
+
+        # Return the response
+        api_response = operations_pb2.Operation()
+        json_format.Parse(response.content, api_response, ignore_unknown_fields=False)
+        return api_response
+
+    def _delete_operation(
+        self,
+        request: operations_pb2.DeleteOperationRequest,
+        *,
+        # TODO(https://github.com/googleapis/python-api-core/issues/723): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
+        timeout: Optional[float] = None,
+        compression: Optional[grpc.Compression] = gapic_v1.method.DEFAULT,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> empty_pb2.Empty:
+        r"""Call the delete operation method over HTTP.
+
+        Args:
+            request (~.operations_pb2.DeleteOperationRequest):
+                The request object. The request message for
+                [Operations.DeleteOperation][google.api_core.operations_v1.Operations.DeleteOperation].
+
+            retry (google.api_core.retry.Retry): Designation of what errors, if any,
+                should be retried.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+        """
+
+        http_options = [
+            {
+                "method": "delete",
+                "uri": "/{}/{{name=**/operations/*}}".format(self._path_prefix),
+            },
+        ]
+        if "google.longrunning.Operations.DeleteOperation" in self._http_options:
+            http_options = self._http_options[
+                "google.longrunning.Operations.DeleteOperation"
+            ]
+
+        request_kwargs = self._convert_protobuf_message_to_dict(request)
+        transcoded_request = path_template.transcode(http_options, **request_kwargs)
+
+        uri = transcoded_request["uri"]
+        method = transcoded_request["method"]
+
+        # Jsonify the query params
+        query_params_request = operations_pb2.DeleteOperationRequest()
+        json_format.ParseDict(transcoded_request["query_params"], query_params_request)
+        query_params = json_format.MessageToDict(
+            query_params_request,
+            preserving_proto_field_name=False,
+            use_integers_for_enums=False,
+        )
+
+        # Send the request
+        headers = dict(metadata)
+        headers["Content-Type"] = "application/json"
+        # TODO(https://github.com/googleapis/python-api-core/issues/721): Update incorrect use of `uri`` variable name.
+        response = getattr(self._session, method)(
+            "{host}{uri}".format(host=self._host, uri=uri),
+            timeout=timeout,
+            headers=headers,
+            params=rest_helpers.flatten_query_params(query_params),
+        )
+
+        # In case of error, raise the appropriate core_exceptions.GoogleAPICallError exception
+        # subclass.
+        if response.status_code >= 400:
+            raise core_exceptions.from_http_response(response)
+
+        return empty_pb2.Empty()
+
+    def _cancel_operation(
+        self,
+        request: operations_pb2.CancelOperationRequest,
+        *,
+        # TODO(https://github.com/googleapis/python-api-core/issues/723): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
+        timeout: Optional[float] = None,
+        compression: Optional[grpc.Compression] = gapic_v1.method.DEFAULT,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> empty_pb2.Empty:
+        r"""Call the cancel operation method over HTTP.
+
+        Args:
+            request (~.operations_pb2.CancelOperationRequest):
+                The request object. The request message for
+                [Operations.CancelOperation][google.api_core.operations_v1.Operations.CancelOperation].
+
+            retry (google.api_core.retry.Retry): Designation of what errors, if any,
+                should be retried.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+        """
+
+        http_options = [
+            {
+                "method": "post",
+                "uri": "/{}/{{name=**/operations/*}}:cancel".format(self._path_prefix),
+                "body": "*",
+            },
+        ]
+        if "google.longrunning.Operations.CancelOperation" in self._http_options:
+            http_options = self._http_options[
+                "google.longrunning.Operations.CancelOperation"
+            ]
+
+        request_kwargs = self._convert_protobuf_message_to_dict(request)
+        transcoded_request = path_template.transcode(http_options, **request_kwargs)
+
+        # Jsonify the request body
+        body_request = operations_pb2.CancelOperationRequest()
+        json_format.ParseDict(transcoded_request["body"], body_request)
+        body = json_format.MessageToDict(
+            body_request,
+            preserving_proto_field_name=False,
+            use_integers_for_enums=False,
+        )
+        uri = transcoded_request["uri"]
+        method = transcoded_request["method"]
+
+        # Jsonify the query params
+        query_params_request = operations_pb2.CancelOperationRequest()
+        json_format.ParseDict(transcoded_request["query_params"], query_params_request)
+        query_params = json_format.MessageToDict(
+            query_params_request,
+            preserving_proto_field_name=False,
+            use_integers_for_enums=False,
+        )
+
+        # Send the request
+        headers = dict(metadata)
+        headers["Content-Type"] = "application/json"
+        # TODO(https://github.com/googleapis/python-api-core/issues/721): Update incorrect use of `uri`` variable name.
+        response = getattr(self._session, method)(
+            "{host}{uri}".format(host=self._host, uri=uri),
+            timeout=timeout,
+            headers=headers,
+            params=rest_helpers.flatten_query_params(query_params),
+            data=body,
+        )
+
+        # In case of error, raise the appropriate core_exceptions.GoogleAPICallError exception
+        # subclass.
+        if response.status_code >= 400:
+            raise core_exceptions.from_http_response(response)
+
+        return empty_pb2.Empty()
+
+    @property
+    def list_operations(
+        self,
+    ) -> Callable[
+        [operations_pb2.ListOperationsRequest], operations_pb2.ListOperationsResponse
+    ]:
+        return self._list_operations
+
+    @property
+    def get_operation(
+        self,
+    ) -> Callable[[operations_pb2.GetOperationRequest], operations_pb2.Operation]:
+        return self._get_operation
+
+    @property
+    def delete_operation(
+        self,
+    ) -> Callable[[operations_pb2.DeleteOperationRequest], empty_pb2.Empty]:
+        return self._delete_operation
+
+    @property
+    def cancel_operation(
+        self,
+    ) -> Callable[[operations_pb2.CancelOperationRequest], empty_pb2.Empty]:
+        return self._cancel_operation
+
+
+__all__ = ("OperationsRestTransport",)
diff --git a/google/api_core/operations_v1/transports/rest_asyncio.py b/google/api_core/operations_v1/transports/rest_asyncio.py
new file mode 100644
index 00000000..71c20eb8
--- /dev/null
+++ b/google/api_core/operations_v1/transports/rest_asyncio.py
@@ -0,0 +1,560 @@
+# -*- coding: utf-8 -*-
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import json
+from typing import Any, Callable, Coroutine, Dict, Optional, Sequence, Tuple
+
+from google.auth import __version__ as auth_version
+
+try:
+    from google.auth.aio.transport.sessions import AsyncAuthorizedSession  # type: ignore
+except ImportError as e:  # pragma: NO COVER
+    raise ImportError(
+        "The `async_rest` extra of `google-api-core` is required to use long-running operations.  Install it by running "
+        "`pip install google-api-core[async_rest]`."
+    ) from e
+
+from google.api_core import exceptions as core_exceptions  # type: ignore
+from google.api_core import gapic_v1  # type: ignore
+from google.api_core import path_template  # type: ignore
+from google.api_core import rest_helpers  # type: ignore
+from google.api_core import retry_async as retries_async  # type: ignore
+from google.auth.aio import credentials as ga_credentials_async  # type: ignore
+from google.longrunning import operations_pb2  # type: ignore
+from google.protobuf import empty_pb2  # type: ignore
+from google.protobuf import json_format  # type: ignore
+
+from .base import DEFAULT_CLIENT_INFO as BASE_DEFAULT_CLIENT_INFO, OperationsTransport
+
+DEFAULT_CLIENT_INFO = gapic_v1.client_info.ClientInfo(
+    gapic_version=BASE_DEFAULT_CLIENT_INFO.gapic_version,
+    grpc_version=None,
+    rest_version=f"google-auth@{auth_version}",
+)
+
+
+class AsyncOperationsRestTransport(OperationsTransport):
+    """Asynchronous REST backend transport for Operations.
+
+    Manages async long-running operations with an API service.
+
+    When an API method normally takes long time to complete, it can be
+    designed to return [Operation][google.api_core.operations_v1.Operation] to the
+    client, and the client can use this interface to receive the real
+    response asynchronously by polling the operation resource, or pass
+    the operation resource to another API (such as Google Cloud Pub/Sub
+    API) to receive the response. Any API service that returns
+    long-running operations should implement the ``Operations``
+    interface so developers can have a consistent client experience.
+
+    This class defines the same methods as the primary client, so the
+    primary client can load the underlying transport implementation
+    and call it.
+
+    It sends JSON representations of protocol buffers over HTTP/1.1
+    """
+
+    def __init__(
+        self,
+        *,
+        host: str = "longrunning.googleapis.com",
+        credentials: Optional[ga_credentials_async.Credentials] = None,
+        credentials_file: Optional[str] = None,
+        scopes: Optional[Sequence[str]] = None,
+        client_cert_source_for_mtls: Optional[Callable[[], Tuple[bytes, bytes]]] = None,
+        quota_project_id: Optional[str] = None,
+        client_info: gapic_v1.client_info.ClientInfo = DEFAULT_CLIENT_INFO,
+        always_use_jwt_access: Optional[bool] = False,
+        url_scheme: str = "https",
+        http_options: Optional[Dict] = None,
+        path_prefix: str = "v1",
+        # TODO(https://github.com/googleapis/python-api-core/issues/715): Add docstring for `credentials_file` to async REST transport.
+        # TODO(https://github.com/googleapis/python-api-core/issues/716): Add docstring for `scopes` to async REST transport.
+        # TODO(https://github.com/googleapis/python-api-core/issues/717): Add docstring for `quota_project_id` to async REST transport.
+        # TODO(https://github.com/googleapis/python-api-core/issues/718): Add docstring for `client_cert_source` to async REST transport.
+    ) -> None:
+        """Instantiate the transport.
+
+        Args:
+            host (Optional[str]):
+                 The hostname to connect to.
+            credentials (Optional[google.auth.aio.credentials.Credentials]): The
+                authorization credentials to attach to requests. These
+                credentials identify the application to the service; if none
+                are specified, the client will attempt to ascertain the
+                credentials from the environment.
+            client_info (google.api_core.gapic_v1.client_info.ClientInfo):
+                The client info used to send a user-agent string along with
+                API requests. If ``None``, then default info will be used.
+                Generally, you only need to set this if you're developing
+                your own client library.
+            always_use_jwt_access (Optional[bool]): Whether self signed JWT should
+                be used for service account credentials.
+            url_scheme: the protocol scheme for the API endpoint.  Normally
+                "https", but for testing or local servers,
+                "http" can be specified.
+            http_options: a dictionary of http_options for transcoding, to override
+                the defaults from operations.proto.  Each method has an entry
+                with the corresponding http rules as value.
+            path_prefix: path prefix (usually represents API version). Set to
+                "v1" by default.
+
+        """
+        unsupported_params = {
+            # TODO(https://github.com/googleapis/python-api-core/issues/715): Add support for `credentials_file` to async REST transport.
+            "google.api_core.client_options.ClientOptions.credentials_file": credentials_file,
+            # TODO(https://github.com/googleapis/python-api-core/issues/716): Add support for `scopes` to async REST transport.
+            "google.api_core.client_options.ClientOptions.scopes": scopes,
+            # TODO(https://github.com/googleapis/python-api-core/issues/717): Add support for `quota_project_id` to async REST transport.
+            "google.api_core.client_options.ClientOptions.quota_project_id": quota_project_id,
+            # TODO(https://github.com/googleapis/python-api-core/issues/718): Add support for `client_cert_source` to async REST transport.
+            "google.api_core.client_options.ClientOptions.client_cert_source": client_cert_source_for_mtls,
+            # TODO(https://github.com/googleapis/python-api-core/issues/718): Add support for `client_cert_source` to async REST transport.
+            "google.api_core.client_options.ClientOptions.client_cert_source": client_cert_source_for_mtls,
+        }
+        provided_unsupported_params = [
+            name for name, value in unsupported_params.items() if value is not None
+        ]
+        if provided_unsupported_params:
+            raise core_exceptions.AsyncRestUnsupportedParameterError(
+                f"The following provided parameters are not supported for `transport=rest_asyncio`: {', '.join(provided_unsupported_params)}"
+            )
+
+        super().__init__(
+            host=host,
+            # TODO(https://github.com/googleapis/python-api-core/issues/709): Remove `type: ignore` when the linked issue is resolved.
+            credentials=credentials,  # type: ignore
+            client_info=client_info,
+            # TODO(https://github.com/googleapis/python-api-core/issues/725): Set always_use_jwt_access token when supported.
+            always_use_jwt_access=False,
+        )
+        # TODO(https://github.com/googleapis/python-api-core/issues/708): add support for
+        # `default_host` in AsyncAuthorizedSession for feature parity with the synchronous
+        # code.
+        # TODO(https://github.com/googleapis/python-api-core/issues/709): Remove `type: ignore` when the linked issue is resolved.
+        self._session = AsyncAuthorizedSession(self._credentials)  # type: ignore
+        # TODO(https://github.com/googleapis/python-api-core/issues/720): Add wrap logic directly to the property methods for callables.
+        self._prep_wrapped_messages(client_info)
+        self._http_options = http_options or {}
+        self._path_prefix = path_prefix
+
+    def _prep_wrapped_messages(self, client_info):
+        # Precompute the wrapped methods.
+        self._wrapped_methods = {
+            self.list_operations: gapic_v1.method_async.wrap_method(
+                self.list_operations,
+                default_retry=retries_async.AsyncRetry(
+                    initial=0.5,
+                    maximum=10.0,
+                    multiplier=2.0,
+                    predicate=retries_async.if_exception_type(
+                        core_exceptions.ServiceUnavailable,
+                    ),
+                    deadline=10.0,
+                ),
+                default_timeout=10.0,
+                client_info=client_info,
+                kind="rest_asyncio",
+            ),
+            self.get_operation: gapic_v1.method_async.wrap_method(
+                self.get_operation,
+                default_retry=retries_async.AsyncRetry(
+                    initial=0.5,
+                    maximum=10.0,
+                    multiplier=2.0,
+                    predicate=retries_async.if_exception_type(
+                        core_exceptions.ServiceUnavailable,
+                    ),
+                    deadline=10.0,
+                ),
+                default_timeout=10.0,
+                client_info=client_info,
+                kind="rest_asyncio",
+            ),
+            self.delete_operation: gapic_v1.method_async.wrap_method(
+                self.delete_operation,
+                default_retry=retries_async.AsyncRetry(
+                    initial=0.5,
+                    maximum=10.0,
+                    multiplier=2.0,
+                    predicate=retries_async.if_exception_type(
+                        core_exceptions.ServiceUnavailable,
+                    ),
+                    deadline=10.0,
+                ),
+                default_timeout=10.0,
+                client_info=client_info,
+                kind="rest_asyncio",
+            ),
+            self.cancel_operation: gapic_v1.method_async.wrap_method(
+                self.cancel_operation,
+                default_retry=retries_async.AsyncRetry(
+                    initial=0.5,
+                    maximum=10.0,
+                    multiplier=2.0,
+                    predicate=retries_async.if_exception_type(
+                        core_exceptions.ServiceUnavailable,
+                    ),
+                    deadline=10.0,
+                ),
+                default_timeout=10.0,
+                client_info=client_info,
+                kind="rest_asyncio",
+            ),
+        }
+
+    async def _list_operations(
+        self,
+        request: operations_pb2.ListOperationsRequest,
+        *,
+        # TODO(https://github.com/googleapis/python-api-core/issues/722): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry=gapic_v1.method_async.DEFAULT,
+        timeout: Optional[float] = None,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> operations_pb2.ListOperationsResponse:
+        r"""Asynchronously call the list operations method over HTTP.
+
+        Args:
+            request (~.operations_pb2.ListOperationsRequest):
+                The request object. The request message for
+                [Operations.ListOperations][google.api_core.operations_v1.Operations.ListOperations].
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+
+        Returns:
+            ~.operations_pb2.ListOperationsResponse:
+                The response message for
+                [Operations.ListOperations][google.api_core.operations_v1.Operations.ListOperations].
+
+        """
+
+        http_options = [
+            {
+                "method": "get",
+                "uri": "/{}/{{name=**}}/operations".format(self._path_prefix),
+            },
+        ]
+        if "google.longrunning.Operations.ListOperations" in self._http_options:
+            http_options = self._http_options[
+                "google.longrunning.Operations.ListOperations"
+            ]
+
+        request_kwargs = self._convert_protobuf_message_to_dict(request)
+        transcoded_request = path_template.transcode(http_options, **request_kwargs)
+
+        uri = transcoded_request["uri"]
+        method = transcoded_request["method"]
+
+        # Jsonify the query params
+        query_params_request = operations_pb2.ListOperationsRequest()
+        json_format.ParseDict(transcoded_request["query_params"], query_params_request)
+        query_params = json_format.MessageToDict(
+            query_params_request,
+            preserving_proto_field_name=False,
+            use_integers_for_enums=False,
+        )
+
+        # Send the request
+        headers = dict(metadata)
+        headers["Content-Type"] = "application/json"
+        # TODO(https://github.com/googleapis/python-api-core/issues/721): Update incorrect use of `uri`` variable name.
+        response = await getattr(self._session, method)(
+            "{host}{uri}".format(host=self._host, uri=uri),
+            timeout=timeout,
+            headers=headers,
+            params=rest_helpers.flatten_query_params(query_params),
+        )
+        content = await response.read()
+
+        # In case of error, raise the appropriate core_exceptions.GoogleAPICallError exception
+        # subclass.
+        if response.status_code >= 400:
+            payload = json.loads(content.decode("utf-8"))
+            request_url = "{host}{uri}".format(host=self._host, uri=uri)
+            raise core_exceptions.format_http_response_error(response, method, request_url, payload)  # type: ignore
+
+        # Return the response
+        api_response = operations_pb2.ListOperationsResponse()
+        json_format.Parse(content, api_response, ignore_unknown_fields=False)
+        return api_response
+
+    async def _get_operation(
+        self,
+        request: operations_pb2.GetOperationRequest,
+        *,
+        # TODO(https://github.com/googleapis/python-api-core/issues/722): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry=gapic_v1.method_async.DEFAULT,
+        timeout: Optional[float] = None,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> operations_pb2.Operation:
+        r"""Asynchronously call the get operation method over HTTP.
+
+        Args:
+            request (~.operations_pb2.GetOperationRequest):
+                The request object. The request message for
+                [Operations.GetOperation][google.api_core.operations_v1.Operations.GetOperation].
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+
+        Returns:
+            ~.operations_pb2.Operation:
+                This resource represents a long-
+                running operation that is the result of a
+                network API call.
+
+        """
+
+        http_options = [
+            {
+                "method": "get",
+                "uri": "/{}/{{name=**/operations/*}}".format(self._path_prefix),
+            },
+        ]
+        if "google.longrunning.Operations.GetOperation" in self._http_options:
+            http_options = self._http_options[
+                "google.longrunning.Operations.GetOperation"
+            ]
+
+        request_kwargs = self._convert_protobuf_message_to_dict(request)
+        transcoded_request = path_template.transcode(http_options, **request_kwargs)
+
+        uri = transcoded_request["uri"]
+        method = transcoded_request["method"]
+
+        # Jsonify the query params
+        query_params_request = operations_pb2.GetOperationRequest()
+        json_format.ParseDict(transcoded_request["query_params"], query_params_request)
+        query_params = json_format.MessageToDict(
+            query_params_request,
+            preserving_proto_field_name=False,
+            use_integers_for_enums=False,
+        )
+
+        # Send the request
+        headers = dict(metadata)
+        headers["Content-Type"] = "application/json"
+        # TODO(https://github.com/googleapis/python-api-core/issues/721): Update incorrect use of `uri`` variable name.
+        response = await getattr(self._session, method)(
+            "{host}{uri}".format(host=self._host, uri=uri),
+            timeout=timeout,
+            headers=headers,
+            params=rest_helpers.flatten_query_params(query_params),
+        )
+        content = await response.read()
+
+        # In case of error, raise the appropriate core_exceptions.GoogleAPICallError exception
+        # subclass.
+        if response.status_code >= 400:
+            payload = json.loads(content.decode("utf-8"))
+            request_url = "{host}{uri}".format(host=self._host, uri=uri)
+            raise core_exceptions.format_http_response_error(response, method, request_url, payload)  # type: ignore
+
+        # Return the response
+        api_response = operations_pb2.Operation()
+        json_format.Parse(content, api_response, ignore_unknown_fields=False)
+        return api_response
+
+    async def _delete_operation(
+        self,
+        request: operations_pb2.DeleteOperationRequest,
+        *,
+        # TODO(https://github.com/googleapis/python-api-core/issues/722): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry=gapic_v1.method_async.DEFAULT,
+        timeout: Optional[float] = None,
+        metadata: Sequence[Tuple[str, str]] = (),
+    ) -> empty_pb2.Empty:
+        r"""Asynchronously call the delete operation method over HTTP.
+
+        Args:
+            request (~.operations_pb2.DeleteOperationRequest):
+                The request object. The request message for
+                [Operations.DeleteOperation][google.api_core.operations_v1.Operations.DeleteOperation].
+
+            retry (google.api_core.retry.Retry): Designation of what errors, if any,
+                should be retried.
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+        """
+
+        http_options = [
+            {
+                "method": "delete",
+                "uri": "/{}/{{name=**/operations/*}}".format(self._path_prefix),
+            },
+        ]
+        if "google.longrunning.Operations.DeleteOperation" in self._http_options:
+            http_options = self._http_options[
+                "google.longrunning.Operations.DeleteOperation"
+            ]
+
+        request_kwargs = self._convert_protobuf_message_to_dict(request)
+        transcoded_request = path_template.transcode(http_options, **request_kwargs)
+
+        uri = transcoded_request["uri"]
+        method = transcoded_request["method"]
+
+        # Jsonify the query params
+        query_params_request = operations_pb2.DeleteOperationRequest()
+        json_format.ParseDict(transcoded_request["query_params"], query_params_request)
+        query_params = json_format.MessageToDict(
+            query_params_request,
+            preserving_proto_field_name=False,
+            use_integers_for_enums=False,
+        )
+
+        # Send the request
+        headers = dict(metadata)
+        headers["Content-Type"] = "application/json"
+        # TODO(https://github.com/googleapis/python-api-core/issues/721): Update incorrect use of `uri`` variable name.
+        response = await getattr(self._session, method)(
+            "{host}{uri}".format(host=self._host, uri=uri),
+            timeout=timeout,
+            headers=headers,
+            params=rest_helpers.flatten_query_params(query_params),
+        )
+
+        # In case of error, raise the appropriate core_exceptions.GoogleAPICallError exception
+        # subclass.
+        if response.status_code >= 400:
+            content = await response.read()
+            payload = json.loads(content.decode("utf-8"))
+            request_url = "{host}{uri}".format(host=self._host, uri=uri)
+            raise core_exceptions.format_http_response_error(response, method, request_url, payload)  # type: ignore
+
+        return empty_pb2.Empty()
+
+    async def _cancel_operation(
+        self,
+        request: operations_pb2.CancelOperationRequest,
+        *,
+        # TODO(https://github.com/googleapis/python-api-core/issues/722): Leverage `retry`
+        # to allow configuring retryable error codes.
+        retry=gapic_v1.method_async.DEFAULT,
+        timeout: Optional[float] = None,
+        metadata: Sequence[Tuple[str, str]] = (),
+        # TODO(https://github.com/googleapis/python-api-core/issues/722): Add `retry` parameter
+        # to allow configuring retryable error codes.
+    ) -> empty_pb2.Empty:
+        r"""Asynchronously call the cancel operation method over HTTP.
+
+        Args:
+            request (~.operations_pb2.CancelOperationRequest):
+                The request object. The request message for
+                [Operations.CancelOperation][google.api_core.operations_v1.Operations.CancelOperation].
+            timeout (float): The timeout for this request.
+            metadata (Sequence[Tuple[str, str]]): Strings which should be
+                sent along with the request as metadata.
+        """
+
+        http_options = [
+            {
+                "method": "post",
+                "uri": "/{}/{{name=**/operations/*}}:cancel".format(self._path_prefix),
+                "body": "*",
+            },
+        ]
+        if "google.longrunning.Operations.CancelOperation" in self._http_options:
+            http_options = self._http_options[
+                "google.longrunning.Operations.CancelOperation"
+            ]
+
+        request_kwargs = self._convert_protobuf_message_to_dict(request)
+        transcoded_request = path_template.transcode(http_options, **request_kwargs)
+
+        # Jsonify the request body
+        body_request = operations_pb2.CancelOperationRequest()
+        json_format.ParseDict(transcoded_request["body"], body_request)
+        body = json_format.MessageToDict(
+            body_request,
+            preserving_proto_field_name=False,
+            use_integers_for_enums=False,
+        )
+        uri = transcoded_request["uri"]
+        method = transcoded_request["method"]
+
+        # Jsonify the query params
+        query_params_request = operations_pb2.CancelOperationRequest()
+        json_format.ParseDict(transcoded_request["query_params"], query_params_request)
+        query_params = json_format.MessageToDict(
+            query_params_request,
+            preserving_proto_field_name=False,
+            use_integers_for_enums=False,
+        )
+
+        # Send the request
+        headers = dict(metadata)
+        headers["Content-Type"] = "application/json"
+        # TODO(https://github.com/googleapis/python-api-core/issues/721): Update incorrect use of `uri`` variable name.
+        response = await getattr(self._session, method)(
+            "{host}{uri}".format(host=self._host, uri=uri),
+            timeout=timeout,
+            headers=headers,
+            params=rest_helpers.flatten_query_params(query_params),
+            data=body,
+        )
+
+        # In case of error, raise the appropriate core_exceptions.GoogleAPICallError exception
+        # subclass.
+        if response.status_code >= 400:
+            content = await response.read()
+            payload = json.loads(content.decode("utf-8"))
+            request_url = "{host}{uri}".format(host=self._host, uri=uri)
+            raise core_exceptions.format_http_response_error(response, method, request_url, payload)  # type: ignore
+
+        return empty_pb2.Empty()
+
+    @property
+    def list_operations(
+        self,
+    ) -> Callable[
+        [operations_pb2.ListOperationsRequest],
+        Coroutine[Any, Any, operations_pb2.ListOperationsResponse],
+    ]:
+        return self._list_operations
+
+    @property
+    def get_operation(
+        self,
+    ) -> Callable[
+        [operations_pb2.GetOperationRequest],
+        Coroutine[Any, Any, operations_pb2.Operation],
+    ]:
+        return self._get_operation
+
+    @property
+    def delete_operation(
+        self,
+    ) -> Callable[
+        [operations_pb2.DeleteOperationRequest], Coroutine[Any, Any, empty_pb2.Empty]
+    ]:
+        return self._delete_operation
+
+    @property
+    def cancel_operation(
+        self,
+    ) -> Callable[
+        [operations_pb2.CancelOperationRequest], Coroutine[Any, Any, empty_pb2.Empty]
+    ]:
+        return self._cancel_operation
+
+
+__all__ = ("AsyncOperationsRestTransport",)
diff --git a/google/api_core/page_iterator.py b/google/api_core/page_iterator.py
index 7ddc5cbc..23761ec4 100644
--- a/google/api_core/page_iterator.py
+++ b/google/api_core/page_iterator.py
@@ -448,7 +448,7 @@ class _GAXIterator(Iterator):
         page_iter (google.gax.PageIterator): A GAX page iterator to be wrapped
             to conform to the :class:`Iterator` interface.
         item_to_value (Callable[Iterator, Any]): Callable to convert an item
-            from the the protobuf response into a native object. Will
+            from the protobuf response into a native object. Will
             be called with the iterator and a single item.
         max_results (int): The maximum number of results to fetch.
 
diff --git a/google/api_core/path_template.py b/google/api_core/path_template.py
index c5969c14..b8ebb2af 100644
--- a/google/api_core/path_template.py
+++ b/google/api_core/path_template.py
@@ -25,6 +25,8 @@
 
 from __future__ import unicode_literals
 
+from collections import deque
+import copy
 import functools
 import re
 
@@ -64,7 +66,7 @@ def _expand_variable_match(positional_vars, named_vars, match):
     """Expand a matched variable with its value.
 
     Args:
-        positional_vars (list): A list of positonal variables. This list will
+        positional_vars (list): A list of positional variables. This list will
             be modified.
         named_vars (dict): A dictionary of named variables.
         match (re.Match): A regular expression match.
@@ -170,6 +172,56 @@ def _generate_pattern_for_template(tmpl):
     return _VARIABLE_RE.sub(_replace_variable_with_pattern, tmpl)
 
 
+def get_field(request, field):
+    """Get the value of a field from a given dictionary.
+
+    Args:
+        request (dict | Message): A dictionary or a Message object.
+        field (str): The key to the request in dot notation.
+
+    Returns:
+        The value of the field.
+    """
+    parts = field.split(".")
+    value = request
+
+    for part in parts:
+        if not isinstance(value, dict):
+            value = getattr(value, part, None)
+        else:
+            value = value.get(part)
+    if isinstance(value, dict):
+        return
+    return value
+
+
+def delete_field(request, field):
+    """Delete the value of a field from a given dictionary.
+
+    Args:
+        request (dict | Message): A dictionary object or a Message.
+        field (str): The key to the request in dot notation.
+    """
+    parts = deque(field.split("."))
+    while len(parts) > 1:
+        part = parts.popleft()
+        if not isinstance(request, dict):
+            if hasattr(request, part):
+                request = getattr(request, part, None)
+            else:
+                return
+        else:
+            request = request.get(part)
+    part = parts.popleft()
+    if not isinstance(request, dict):
+        if hasattr(request, part):
+            request.ClearField(part)
+        else:
+            return
+    else:
+        request.pop(part, None)
+
+
 def validate(tmpl, path):
     """Validate a path against the path template.
 
@@ -193,3 +245,102 @@ def validate(tmpl, path):
     """
     pattern = _generate_pattern_for_template(tmpl) + "$"
     return True if re.match(pattern, path) is not None else False
+
+
+def transcode(http_options, message=None, **request_kwargs):
+    """Transcodes a grpc request pattern into a proper HTTP request following the rules outlined here,
+    https://github.com/googleapis/googleapis/blob/master/google/api/http.proto#L44-L312
+
+     Args:
+         http_options (list(dict)): A list of dicts which consist of these keys,
+             'method'    (str): The http method
+             'uri'       (str): The path template
+             'body'      (str): The body field name (optional)
+             (This is a simplified representation of the proto option `google.api.http`)
+
+         message (Message) : A request object (optional)
+         request_kwargs (dict) : A dict representing the request object
+
+     Returns:
+         dict: The transcoded request with these keys,
+             'method'        (str)   : The http method
+             'uri'           (str)   : The expanded uri
+             'body'          (dict | Message)  : A dict or a Message representing the body (optional)
+             'query_params'  (dict | Message)  : A dict or Message mapping query parameter variables and values
+
+     Raises:
+         ValueError: If the request does not match the given template.
+    """
+    transcoded_value = message or request_kwargs
+    bindings = []
+    for http_option in http_options:
+        request = {}
+
+        # Assign path
+        uri_template = http_option["uri"]
+        fields = [
+            (m.group("name"), m.group("template"))
+            for m in _VARIABLE_RE.finditer(uri_template)
+        ]
+        bindings.append((uri_template, fields))
+
+        path_args = {field: get_field(transcoded_value, field) for field, _ in fields}
+        request["uri"] = expand(uri_template, **path_args)
+
+        if not validate(uri_template, request["uri"]) or not all(path_args.values()):
+            continue
+
+        # Remove fields used in uri path from request
+        leftovers = copy.deepcopy(transcoded_value)
+        for path_field, _ in fields:
+            delete_field(leftovers, path_field)
+
+        # Assign body and query params
+        body = http_option.get("body")
+
+        if body:
+            if body == "*":
+                request["body"] = leftovers
+                if message:
+                    request["query_params"] = message.__class__()
+                else:
+                    request["query_params"] = {}
+            else:
+                try:
+                    if message:
+                        request["body"] = getattr(leftovers, body)
+                        delete_field(leftovers, body)
+                    else:
+                        request["body"] = leftovers.pop(body)
+                except (KeyError, AttributeError):
+                    continue
+                request["query_params"] = leftovers
+        else:
+            request["query_params"] = leftovers
+        request["method"] = http_option["method"]
+        return request
+
+    bindings_description = [
+        '\n\tURI: "{}"'
+        "\n\tRequired request fields:\n\t\t{}".format(
+            uri,
+            "\n\t\t".join(
+                [
+                    'field: "{}", pattern: "{}"'.format(n, p if p else "*")
+                    for n, p in fields
+                ]
+            ),
+        )
+        for uri, fields in bindings
+    ]
+
+    raise ValueError(
+        "Invalid request."
+        "\nSome of the fields of the request message are either not initialized or "
+        "initialized with an invalid value."
+        "\nPlease make sure your request matches at least one accepted HTTP binding."
+        "\nTo match a binding the request message must have all the required fields "
+        "initialized with values matching their patterns as listed below:{}".format(
+            "\n".join(bindings_description)
+        )
+    )
diff --git a/google/api_core/protobuf_helpers.py b/google/api_core/protobuf_helpers.py
index 896e89c1..30cd7c85 100644
--- a/google/api_core/protobuf_helpers.py
+++ b/google/api_core/protobuf_helpers.py
@@ -63,9 +63,7 @@ def from_any_pb(pb_type, any_pb):
     # Unpack the Any object and populate the protobuf message instance.
     if not any_pb.Unpack(msg_pb):
         raise TypeError(
-            "Could not convert {} to {}".format(
-                any_pb.__class__.__name__, pb_type.__name__
-            )
+            f"Could not convert `{any_pb.TypeName()}` with underlying type `google.protobuf.any_pb2.Any` to `{msg_pb.DESCRIPTOR.full_name}`"
         )
 
     # Done; return the message.
@@ -288,10 +286,10 @@ def field_mask(original, modified):
 
     Args:
         original (~google.protobuf.message.Message): the original message.
-            If set to None, this field will be interpretted as an empty
+            If set to None, this field will be interpreted as an empty
             message.
         modified (~google.protobuf.message.Message): the modified message.
-            If set to None, this field will be interpretted as an empty
+            If set to None, this field will be interpreted as an empty
             message.
 
     Returns:
@@ -313,7 +311,7 @@ def field_mask(original, modified):
         modified = copy.deepcopy(original)
         modified.Clear()
 
-    if type(original) != type(modified):
+    if not isinstance(original, type(modified)):
         raise ValueError(
             "expected that both original and modified should be of the "
             'same type, received "{!r}" and "{!r}".'.format(
diff --git a/google/api_core/py.typed b/google/api_core/py.typed
new file mode 100644
index 00000000..1d5517b1
--- /dev/null
+++ b/google/api_core/py.typed
@@ -0,0 +1,2 @@
+# Marker file for PEP 561.
+# The google-api-core package uses inline types.
diff --git a/google/api_core/rest_helpers.py b/google/api_core/rest_helpers.py
new file mode 100644
index 00000000..a78822f1
--- /dev/null
+++ b/google/api_core/rest_helpers.py
@@ -0,0 +1,109 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helpers for rest transports."""
+
+import functools
+import operator
+
+
+def flatten_query_params(obj, strict=False):
+    """Flatten a dict into a list of (name,value) tuples.
+
+    The result is suitable for setting query params on an http request.
+
+    .. code-block:: python
+
+        >>> obj = {'a':
+        ...         {'b':
+        ...           {'c': ['x', 'y', 'z']} },
+        ...      'd': 'uvw',
+        ...      'e': True, }
+        >>> flatten_query_params(obj, strict=True)
+        [('a.b.c', 'x'), ('a.b.c', 'y'), ('a.b.c', 'z'), ('d', 'uvw'), ('e', 'true')]
+
+    Note that, as described in
+    https://github.com/googleapis/googleapis/blob/48d9fb8c8e287c472af500221c6450ecd45d7d39/google/api/http.proto#L117,
+    repeated fields (i.e. list-valued fields) may only contain primitive types (not lists or dicts).
+    This is enforced in this function.
+
+    Args:
+      obj: a possibly nested dictionary (from json), or None
+      strict: a bool, defaulting to False, to enforce that all values in the
+              result tuples be strings and, if boolean, lower-cased.
+
+    Returns: a list of tuples, with each tuple having a (possibly) multi-part name
+      and a scalar value.
+
+    Raises:
+      TypeError if obj is not a dict or None
+      ValueError if obj contains a list of non-primitive values.
+    """
+
+    if obj is not None and not isinstance(obj, dict):
+        raise TypeError("flatten_query_params must be called with dict object")
+
+    return _flatten(obj, key_path=[], strict=strict)
+
+
+def _flatten(obj, key_path, strict=False):
+    if obj is None:
+        return []
+    if isinstance(obj, dict):
+        return _flatten_dict(obj, key_path=key_path, strict=strict)
+    if isinstance(obj, list):
+        return _flatten_list(obj, key_path=key_path, strict=strict)
+    return _flatten_value(obj, key_path=key_path, strict=strict)
+
+
+def _is_primitive_value(obj):
+    if obj is None:
+        return False
+
+    if isinstance(obj, (list, dict)):
+        raise ValueError("query params may not contain repeated dicts or lists")
+
+    return True
+
+
+def _flatten_value(obj, key_path, strict=False):
+    return [(".".join(key_path), _canonicalize(obj, strict=strict))]
+
+
+def _flatten_dict(obj, key_path, strict=False):
+    items = (
+        _flatten(value, key_path=key_path + [key], strict=strict)
+        for key, value in obj.items()
+    )
+    return functools.reduce(operator.concat, items, [])
+
+
+def _flatten_list(elems, key_path, strict=False):
+    # Only lists of scalar values are supported.
+    # The name (key_path) is repeated for each value.
+    items = (
+        _flatten_value(elem, key_path=key_path, strict=strict)
+        for elem in elems
+        if _is_primitive_value(elem)
+    )
+    return functools.reduce(operator.concat, items, [])
+
+
+def _canonicalize(obj, strict=False):
+    if strict:
+        value = str(obj)
+        if isinstance(obj, bool):
+            value = value.lower()
+        return value
+    return obj
diff --git a/google/api_core/rest_streaming.py b/google/api_core/rest_streaming.py
new file mode 100644
index 00000000..84aa270c
--- /dev/null
+++ b/google/api_core/rest_streaming.py
@@ -0,0 +1,66 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helpers for server-side streaming in REST."""
+
+from typing import Union
+
+import proto
+import requests
+import google.protobuf.message
+from google.api_core._rest_streaming_base import BaseResponseIterator
+
+
+class ResponseIterator(BaseResponseIterator):
+    """Iterator over REST API responses.
+
+    Args:
+        response (requests.Response): An API response object.
+        response_message_cls (Union[proto.Message, google.protobuf.message.Message]): A response
+        class expected to be returned from an API.
+
+    Raises:
+        ValueError:
+            - If `response_message_cls` is not a subclass of `proto.Message` or `google.protobuf.message.Message`.
+    """
+
+    def __init__(
+        self,
+        response: requests.Response,
+        response_message_cls: Union[proto.Message, google.protobuf.message.Message],
+    ):
+        self._response = response
+        # Inner iterator over HTTP response's content.
+        self._response_itr = self._response.iter_content(decode_unicode=True)
+        super(ResponseIterator, self).__init__(
+            response_message_cls=response_message_cls
+        )
+
+    def cancel(self):
+        """Cancel existing streaming operation."""
+        self._response.close()
+
+    def __next__(self):
+        while not self._ready_objs:
+            try:
+                chunk = next(self._response_itr)
+                self._process_chunk(chunk)
+            except StopIteration as e:
+                if self._level > 0:
+                    raise ValueError("Unfinished stream: %s" % self._obj)
+                raise e
+        return self._grab()
+
+    def __iter__(self):
+        return self
diff --git a/google/api_core/rest_streaming_async.py b/google/api_core/rest_streaming_async.py
new file mode 100644
index 00000000..370c2b53
--- /dev/null
+++ b/google/api_core/rest_streaming_async.py
@@ -0,0 +1,89 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helpers for asynchronous server-side streaming in REST."""
+
+from typing import Union
+
+import proto
+
+try:
+    import google.auth.aio.transport
+except ImportError as e:  # pragma: NO COVER
+    raise ImportError(
+        "`google-api-core[async_rest]` is required to use asynchronous rest streaming. "
+        "Install the `async_rest` extra of `google-api-core` using "
+        "`pip install google-api-core[async_rest]`."
+    ) from e
+
+import google.protobuf.message
+from google.api_core._rest_streaming_base import BaseResponseIterator
+
+
+class AsyncResponseIterator(BaseResponseIterator):
+    """Asynchronous Iterator over REST API responses.
+
+    Args:
+        response (google.auth.aio.transport.Response): An API response object.
+        response_message_cls (Union[proto.Message, google.protobuf.message.Message]): A response
+        class expected to be returned from an API.
+
+    Raises:
+        ValueError:
+            - If `response_message_cls` is not a subclass of `proto.Message` or `google.protobuf.message.Message`.
+    """
+
+    def __init__(
+        self,
+        response: google.auth.aio.transport.Response,
+        response_message_cls: Union[proto.Message, google.protobuf.message.Message],
+    ):
+        self._response = response
+        self._chunk_size = 1024
+        # TODO(https://github.com/googleapis/python-api-core/issues/703): mypy does not recognize the abstract content
+        # method as an async generator as it looks for the `yield` keyword in the implementation.
+        # Given that the abstract method is not implemented, mypy fails to recognize it as an async generator.
+        # mypy warnings are silenced until the linked issue is resolved.
+        self._response_itr = self._response.content(self._chunk_size).__aiter__()  # type: ignore
+        super(AsyncResponseIterator, self).__init__(
+            response_message_cls=response_message_cls
+        )
+
+    async def __aenter__(self):
+        return self
+
+    async def cancel(self):
+        """Cancel existing streaming operation."""
+        await self._response.close()
+
+    async def __anext__(self):
+        while not self._ready_objs:
+            try:
+                chunk = await self._response_itr.__anext__()
+                chunk = chunk.decode("utf-8")
+                self._process_chunk(chunk)
+            except StopAsyncIteration as e:
+                if self._level > 0:
+                    raise ValueError("i Unfinished stream: %s" % self._obj)
+                raise e
+            except ValueError as e:
+                raise e
+        return self._grab()
+
+    def __aiter__(self):
+        return self
+
+    async def __aexit__(self, exc_type, exc, tb):
+        """Cancel existing async streaming operation."""
+        await self._response.close()
diff --git a/google/api_core/retry.py b/google/api_core/retry.py
deleted file mode 100644
index d39f97c1..00000000
--- a/google/api_core/retry.py
+++ /dev/null
@@ -1,363 +0,0 @@
-# Copyright 2017 Google LLC
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-"""Helpers for retrying functions with exponential back-off.
-
-The :class:`Retry` decorator can be used to retry functions that raise
-exceptions using exponential backoff. Because a exponential sleep algorithm is
-used, the retry is limited by a `deadline`. The deadline is the maxmimum amount
-of time a method can block. This is used instead of total number of retries
-because it is difficult to ascertain the amount of time a function can block
-when using total number of retries and exponential backoff.
-
-By default, this decorator will retry transient
-API errors (see :func:`if_transient_error`). For example:
-
-.. code-block:: python
-
-    @retry.Retry()
-    def call_flaky_rpc():
-        return client.flaky_rpc()
-
-    # Will retry flaky_rpc() if it raises transient API errors.
-    result = call_flaky_rpc()
-
-You can pass a custom predicate to retry on different exceptions, such as
-waiting for an eventually consistent item to be available:
-
-.. code-block:: python
-
-    @retry.Retry(predicate=if_exception_type(exceptions.NotFound))
-    def check_if_exists():
-        return client.does_thing_exist()
-
-    is_available = check_if_exists()
-
-Some client library methods apply retry automatically. These methods can accept
-a ``retry`` parameter that allows you to configure the behavior:
-
-.. code-block:: python
-
-    my_retry = retry.Retry(deadline=60)
-    result = client.some_method(retry=my_retry)
-
-"""
-
-from __future__ import unicode_literals
-
-import datetime
-import functools
-import logging
-import random
-import time
-
-import requests.exceptions
-
-from google.api_core import datetime_helpers
-from google.api_core import exceptions
-from google.auth import exceptions as auth_exceptions
-
-_LOGGER = logging.getLogger(__name__)
-_DEFAULT_INITIAL_DELAY = 1.0  # seconds
-_DEFAULT_MAXIMUM_DELAY = 60.0  # seconds
-_DEFAULT_DELAY_MULTIPLIER = 2.0
-_DEFAULT_DEADLINE = 60.0 * 2.0  # seconds
-
-
-def if_exception_type(*exception_types):
-    """Creates a predicate to check if the exception is of a given type.
-
-    Args:
-        exception_types (Sequence[:func:`type`]): The exception types to check
-            for.
-
-    Returns:
-        Callable[Exception]: A predicate that returns True if the provided
-            exception is of the given type(s).
-    """
-
-    def if_exception_type_predicate(exception):
-        """Bound predicate for checking an exception type."""
-        return isinstance(exception, exception_types)
-
-    return if_exception_type_predicate
-
-
-# pylint: disable=invalid-name
-# Pylint sees this as a constant, but it is also an alias that should be
-# considered a function.
-if_transient_error = if_exception_type(
-    exceptions.InternalServerError,
-    exceptions.TooManyRequests,
-    exceptions.ServiceUnavailable,
-    requests.exceptions.ConnectionError,
-    requests.exceptions.ChunkedEncodingError,
-    auth_exceptions.TransportError,
-)
-"""A predicate that checks if an exception is a transient API error.
-
-The following server errors are considered transient:
-
-- :class:`google.api_core.exceptions.InternalServerError` - HTTP 500, gRPC
-    ``INTERNAL(13)`` and its subclasses.
-- :class:`google.api_core.exceptions.TooManyRequests` - HTTP 429
-- :class:`google.api_core.exceptions.ServiceUnavailable` - HTTP 503
-- :class:`google.api_core.exceptions.ResourceExhausted` - gRPC
-    ``RESOURCE_EXHAUSTED(8)``
-"""
-# pylint: enable=invalid-name
-
-
-def exponential_sleep_generator(initial, maximum, multiplier=_DEFAULT_DELAY_MULTIPLIER):
-    """Generates sleep intervals based on the exponential back-off algorithm.
-
-    This implements the `Truncated Exponential Back-off`_ algorithm.
-
-    .. _Truncated Exponential Back-off:
-        https://cloud.google.com/storage/docs/exponential-backoff
-
-    Args:
-        initial (float): The minimum amount of time to delay. This must
-            be greater than 0.
-        maximum (float): The maximum amount of time to delay.
-        multiplier (float): The multiplier applied to the delay.
-
-    Yields:
-        float: successive sleep intervals.
-    """
-    delay = initial
-    while True:
-        # Introduce jitter by yielding a delay that is uniformly distributed
-        # to average out to the delay time.
-        yield min(random.uniform(0.0, delay * 2.0), maximum)
-        delay = delay * multiplier
-
-
-def retry_target(target, predicate, sleep_generator, deadline, on_error=None):
-    """Call a function and retry if it fails.
-
-    This is the lowest-level retry helper. Generally, you'll use the
-    higher-level retry helper :class:`Retry`.
-
-    Args:
-        target(Callable): The function to call and retry. This must be a
-            nullary function - apply arguments with `functools.partial`.
-        predicate (Callable[Exception]): A callable used to determine if an
-            exception raised by the target should be considered retryable.
-            It should return True to retry or False otherwise.
-        sleep_generator (Iterable[float]): An infinite iterator that determines
-            how long to sleep between retries.
-        deadline (float): How long to keep retrying the target. The last sleep
-            period is shortened as necessary, so that the last retry runs at
-            ``deadline`` (and not considerably beyond it).
-        on_error (Callable[Exception]): A function to call while processing a
-            retryable exception.  Any error raised by this function will *not*
-            be caught.
-
-    Returns:
-        Any: the return value of the target function.
-
-    Raises:
-        google.api_core.RetryError: If the deadline is exceeded while retrying.
-        ValueError: If the sleep generator stops yielding values.
-        Exception: If the target raises a method that isn't retryable.
-    """
-    if deadline is not None:
-        deadline_datetime = datetime_helpers.utcnow() + datetime.timedelta(
-            seconds=deadline
-        )
-    else:
-        deadline_datetime = None
-
-    last_exc = None
-
-    for sleep in sleep_generator:
-        try:
-            return target()
-
-        # pylint: disable=broad-except
-        # This function explicitly must deal with broad exceptions.
-        except Exception as exc:
-            if not predicate(exc):
-                raise
-            last_exc = exc
-            if on_error is not None:
-                on_error(exc)
-
-        now = datetime_helpers.utcnow()
-
-        if deadline_datetime is not None:
-            if deadline_datetime <= now:
-                raise exceptions.RetryError(
-                    "Deadline of {:.1f}s exceeded while calling {}".format(
-                        deadline, target
-                    ),
-                    last_exc,
-                ) from last_exc
-            else:
-                time_to_deadline = (deadline_datetime - now).total_seconds()
-                sleep = min(time_to_deadline, sleep)
-
-        _LOGGER.debug(
-            "Retrying due to {}, sleeping {:.1f}s ...".format(last_exc, sleep)
-        )
-        time.sleep(sleep)
-
-    raise ValueError("Sleep generator stopped yielding sleep values.")
-
-
-class Retry(object):
-    """Exponential retry decorator.
-
-    This class is a decorator used to add exponential back-off retry behavior
-    to an RPC call.
-
-    Although the default behavior is to retry transient API errors, a
-    different predicate can be provided to retry other exceptions.
-
-    Args:
-        predicate (Callable[Exception]): A callable that should return ``True``
-            if the given exception is retryable.
-        initial (float): The minimum amount of time to delay in seconds. This
-            must be greater than 0.
-        maximum (float): The maximum amount of time to delay in seconds.
-        multiplier (float): The multiplier applied to the delay.
-        deadline (float): How long to keep retrying in seconds. The last sleep
-            period is shortened as necessary, so that the last retry runs at
-            ``deadline`` (and not considerably beyond it).
-    """
-
-    def __init__(
-        self,
-        predicate=if_transient_error,
-        initial=_DEFAULT_INITIAL_DELAY,
-        maximum=_DEFAULT_MAXIMUM_DELAY,
-        multiplier=_DEFAULT_DELAY_MULTIPLIER,
-        deadline=_DEFAULT_DEADLINE,
-        on_error=None,
-    ):
-        self._predicate = predicate
-        self._initial = initial
-        self._multiplier = multiplier
-        self._maximum = maximum
-        self._deadline = deadline
-        self._on_error = on_error
-
-    def __call__(self, func, on_error=None):
-        """Wrap a callable with retry behavior.
-
-        Args:
-            func (Callable): The callable to add retry behavior to.
-            on_error (Callable[Exception]): A function to call while processing
-                a retryable exception. Any error raised by this function will
-                *not* be caught.
-
-        Returns:
-            Callable: A callable that will invoke ``func`` with retry
-                behavior.
-        """
-        if self._on_error is not None:
-            on_error = self._on_error
-
-        @functools.wraps(func)
-        def retry_wrapped_func(*args, **kwargs):
-            """A wrapper that calls target function with retry."""
-            target = functools.partial(func, *args, **kwargs)
-            sleep_generator = exponential_sleep_generator(
-                self._initial, self._maximum, multiplier=self._multiplier
-            )
-            return retry_target(
-                target,
-                self._predicate,
-                sleep_generator,
-                self._deadline,
-                on_error=on_error,
-            )
-
-        return retry_wrapped_func
-
-    @property
-    def deadline(self):
-        return self._deadline
-
-    def with_deadline(self, deadline):
-        """Return a copy of this retry with the given deadline.
-
-        Args:
-            deadline (float): How long to keep retrying.
-
-        Returns:
-            Retry: A new retry instance with the given deadline.
-        """
-        return Retry(
-            predicate=self._predicate,
-            initial=self._initial,
-            maximum=self._maximum,
-            multiplier=self._multiplier,
-            deadline=deadline,
-            on_error=self._on_error,
-        )
-
-    def with_predicate(self, predicate):
-        """Return a copy of this retry with the given predicate.
-
-        Args:
-            predicate (Callable[Exception]): A callable that should return
-                ``True`` if the given exception is retryable.
-
-        Returns:
-            Retry: A new retry instance with the given predicate.
-        """
-        return Retry(
-            predicate=predicate,
-            initial=self._initial,
-            maximum=self._maximum,
-            multiplier=self._multiplier,
-            deadline=self._deadline,
-            on_error=self._on_error,
-        )
-
-    def with_delay(self, initial=None, maximum=None, multiplier=None):
-        """Return a copy of this retry with the given delay options.
-
-        Args:
-            initial (float): The minimum amount of time to delay. This must
-                be greater than 0.
-            maximum (float): The maximum amount of time to delay.
-            multiplier (float): The multiplier applied to the delay.
-
-        Returns:
-            Retry: A new retry instance with the given predicate.
-        """
-        return Retry(
-            predicate=self._predicate,
-            initial=initial if initial is not None else self._initial,
-            maximum=maximum if maximum is not None else self._maximum,
-            multiplier=multiplier if multiplier is not None else self._multiplier,
-            deadline=self._deadline,
-            on_error=self._on_error,
-        )
-
-    def __str__(self):
-        return (
-            "<Retry predicate={}, initial={:.1f}, maximum={:.1f}, "
-            "multiplier={:.1f}, deadline={:.1f}, on_error={}>".format(
-                self._predicate,
-                self._initial,
-                self._maximum,
-                self._multiplier,
-                self._deadline,
-                self._on_error,
-            )
-        )
diff --git a/google/api_core/retry/__init__.py b/google/api_core/retry/__init__.py
new file mode 100644
index 00000000..1724fdbd
--- /dev/null
+++ b/google/api_core/retry/__init__.py
@@ -0,0 +1,52 @@
+# Copyright 2017 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Retry implementation for Google API client libraries."""
+
+from .retry_base import exponential_sleep_generator
+from .retry_base import if_exception_type
+from .retry_base import if_transient_error
+from .retry_base import build_retry_error
+from .retry_base import RetryFailureReason
+from .retry_unary import Retry
+from .retry_unary import retry_target
+from .retry_unary_async import AsyncRetry
+from .retry_unary_async import retry_target as retry_target_async
+from .retry_streaming import StreamingRetry
+from .retry_streaming import retry_target_stream
+from .retry_streaming_async import AsyncStreamingRetry
+from .retry_streaming_async import retry_target_stream as retry_target_stream_async
+
+# The following imports are for backwards compatibility with https://github.com/googleapis/python-api-core/blob/4d7d2edee2c108d43deb151e6e0fdceb56b73275/google/api_core/retry.py
+#
+# TODO: Revert these imports on the next major version release (https://github.com/googleapis/python-api-core/issues/576)
+from google.api_core import datetime_helpers  # noqa: F401
+from google.api_core import exceptions  # noqa: F401
+from google.auth import exceptions as auth_exceptions  # noqa: F401
+
+__all__ = (
+    "exponential_sleep_generator",
+    "if_exception_type",
+    "if_transient_error",
+    "build_retry_error",
+    "RetryFailureReason",
+    "Retry",
+    "AsyncRetry",
+    "StreamingRetry",
+    "AsyncStreamingRetry",
+    "retry_target",
+    "retry_target_async",
+    "retry_target_stream",
+    "retry_target_stream_async",
+)
diff --git a/google/api_core/retry/retry_base.py b/google/api_core/retry/retry_base.py
new file mode 100644
index 00000000..263b4ccf
--- /dev/null
+++ b/google/api_core/retry/retry_base.py
@@ -0,0 +1,370 @@
+# Copyright 2017 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Shared classes and functions for retrying requests.
+
+:class:`_BaseRetry` is the base class for :class:`Retry`,
+:class:`AsyncRetry`, :class:`StreamingRetry`, and :class:`AsyncStreamingRetry`.
+"""
+
+from __future__ import annotations
+
+import logging
+import random
+import time
+
+from enum import Enum
+from typing import Any, Callable, Optional, Iterator, TYPE_CHECKING
+
+import requests.exceptions
+
+from google.api_core import exceptions
+from google.auth import exceptions as auth_exceptions
+
+if TYPE_CHECKING:
+    import sys
+
+    if sys.version_info >= (3, 11):
+        from typing import Self
+    else:
+        from typing_extensions import Self
+
+_DEFAULT_INITIAL_DELAY = 1.0  # seconds
+_DEFAULT_MAXIMUM_DELAY = 60.0  # seconds
+_DEFAULT_DELAY_MULTIPLIER = 2.0
+_DEFAULT_DEADLINE = 60.0 * 2.0  # seconds
+
+_LOGGER = logging.getLogger("google.api_core.retry")
+
+
+def if_exception_type(
+    *exception_types: type[Exception],
+) -> Callable[[Exception], bool]:
+    """Creates a predicate to check if the exception is of a given type.
+
+    Args:
+        exception_types (Sequence[:func:`type`]): The exception types to check
+            for.
+
+    Returns:
+        Callable[Exception]: A predicate that returns True if the provided
+            exception is of the given type(s).
+    """
+
+    def if_exception_type_predicate(exception: Exception) -> bool:
+        """Bound predicate for checking an exception type."""
+        return isinstance(exception, exception_types)
+
+    return if_exception_type_predicate
+
+
+# pylint: disable=invalid-name
+# Pylint sees this as a constant, but it is also an alias that should be
+# considered a function.
+if_transient_error = if_exception_type(
+    exceptions.InternalServerError,
+    exceptions.TooManyRequests,
+    exceptions.ServiceUnavailable,
+    requests.exceptions.ConnectionError,
+    requests.exceptions.ChunkedEncodingError,
+    auth_exceptions.TransportError,
+)
+"""A predicate that checks if an exception is a transient API error.
+
+The following server errors are considered transient:
+
+- :class:`google.api_core.exceptions.InternalServerError` - HTTP 500, gRPC
+    ``INTERNAL(13)`` and its subclasses.
+- :class:`google.api_core.exceptions.TooManyRequests` - HTTP 429
+- :class:`google.api_core.exceptions.ServiceUnavailable` - HTTP 503
+- :class:`requests.exceptions.ConnectionError`
+- :class:`requests.exceptions.ChunkedEncodingError` - The server declared
+    chunked encoding but sent an invalid chunk.
+- :class:`google.auth.exceptions.TransportError` - Used to indicate an
+    error occurred during an HTTP request.
+"""
+# pylint: enable=invalid-name
+
+
+def exponential_sleep_generator(
+    initial: float, maximum: float, multiplier: float = _DEFAULT_DELAY_MULTIPLIER
+):
+    """Generates sleep intervals based on the exponential back-off algorithm.
+
+    This implements the `Truncated Exponential Back-off`_ algorithm.
+
+    .. _Truncated Exponential Back-off:
+        https://cloud.google.com/storage/docs/exponential-backoff
+
+    Args:
+        initial (float): The minimum amount of time to delay. This must
+            be greater than 0.
+        maximum (float): The maximum amount of time to delay.
+        multiplier (float): The multiplier applied to the delay.
+
+    Yields:
+        float: successive sleep intervals.
+    """
+    max_delay = min(initial, maximum)
+    while True:
+        yield random.uniform(0.0, max_delay)
+        max_delay = min(max_delay * multiplier, maximum)
+
+
+class RetryFailureReason(Enum):
+    """
+    The cause of a failed retry, used when building exceptions
+    """
+
+    TIMEOUT = 0
+    NON_RETRYABLE_ERROR = 1
+
+
+def build_retry_error(
+    exc_list: list[Exception],
+    reason: RetryFailureReason,
+    timeout_val: float | None,
+    **kwargs: Any,
+) -> tuple[Exception, Exception | None]:
+    """
+    Default exception_factory implementation.
+
+    Returns a RetryError if the failure is due to a timeout, otherwise
+    returns the last exception encountered.
+
+    Args:
+      - exc_list: list of exceptions that occurred during the retry
+      - reason: reason for the retry failure.
+            Can be TIMEOUT or NON_RETRYABLE_ERROR
+      - timeout_val: the original timeout value for the retry (in seconds), for use in the exception message
+
+    Returns:
+      - tuple: a tuple of the exception to be raised, and the cause exception if any
+    """
+    if reason == RetryFailureReason.TIMEOUT:
+        # return RetryError with the most recent exception as the cause
+        src_exc = exc_list[-1] if exc_list else None
+        timeout_val_str = f"of {timeout_val:0.1f}s " if timeout_val is not None else ""
+        return (
+            exceptions.RetryError(
+                f"Timeout {timeout_val_str}exceeded",
+                src_exc,
+            ),
+            src_exc,
+        )
+    elif exc_list:
+        # return most recent exception encountered
+        return exc_list[-1], None
+    else:
+        # no exceptions were given in exc_list. Raise generic RetryError
+        return exceptions.RetryError("Unknown error", None), None
+
+
+def _retry_error_helper(
+    exc: Exception,
+    deadline: float | None,
+    sleep_iterator: Iterator[float],
+    error_list: list[Exception],
+    predicate_fn: Callable[[Exception], bool],
+    on_error_fn: Callable[[Exception], None] | None,
+    exc_factory_fn: Callable[
+        [list[Exception], RetryFailureReason, float | None],
+        tuple[Exception, Exception | None],
+    ],
+    original_timeout: float | None,
+) -> float:
+    """
+    Shared logic for handling an error for all retry implementations
+
+    - Raises an error on timeout or non-retryable error
+    - Calls on_error_fn if provided
+    - Logs the error
+
+    Args:
+       - exc: the exception that was raised
+       - deadline: the deadline for the retry, calculated as a diff from time.monotonic()
+       - sleep_iterator: iterator to draw the next backoff value from
+       - error_list: the list of exceptions that have been raised so far
+       - predicate_fn: takes `exc` and returns true if the operation should be retried
+       - on_error_fn: callback to execute when a retryable error occurs
+       - exc_factory_fn: callback used to build the exception to be raised on terminal failure
+       - original_timeout_val: the original timeout value for the retry (in seconds),
+           to be passed to the exception factory for building an error message
+    Returns:
+        - the sleep value chosen before the next attempt
+    """
+    error_list.append(exc)
+    if not predicate_fn(exc):
+        final_exc, source_exc = exc_factory_fn(
+            error_list,
+            RetryFailureReason.NON_RETRYABLE_ERROR,
+            original_timeout,
+        )
+        raise final_exc from source_exc
+    if on_error_fn is not None:
+        on_error_fn(exc)
+    # next_sleep is fetched after the on_error callback, to allow clients
+    # to update sleep_iterator values dynamically in response to errors
+    try:
+        next_sleep = next(sleep_iterator)
+    except StopIteration:
+        raise ValueError("Sleep generator stopped yielding sleep values.") from exc
+    if deadline is not None and time.monotonic() + next_sleep > deadline:
+        final_exc, source_exc = exc_factory_fn(
+            error_list,
+            RetryFailureReason.TIMEOUT,
+            original_timeout,
+        )
+        raise final_exc from source_exc
+    _LOGGER.debug(
+        "Retrying due to {}, sleeping {:.1f}s ...".format(error_list[-1], next_sleep)
+    )
+    return next_sleep
+
+
+class _BaseRetry(object):
+    """
+    Base class for retry configuration objects. This class is intended to capture retry
+    and backoff configuration that is common to both synchronous and asynchronous retries,
+    for both unary and streaming RPCs. It is not intended to be instantiated directly,
+    but rather to be subclassed by the various retry configuration classes.
+    """
+
+    def __init__(
+        self,
+        predicate: Callable[[Exception], bool] = if_transient_error,
+        initial: float = _DEFAULT_INITIAL_DELAY,
+        maximum: float = _DEFAULT_MAXIMUM_DELAY,
+        multiplier: float = _DEFAULT_DELAY_MULTIPLIER,
+        timeout: Optional[float] = _DEFAULT_DEADLINE,
+        on_error: Optional[Callable[[Exception], Any]] = None,
+        **kwargs: Any,
+    ) -> None:
+        self._predicate = predicate
+        self._initial = initial
+        self._multiplier = multiplier
+        self._maximum = maximum
+        self._timeout = kwargs.get("deadline", timeout)
+        self._deadline = self._timeout
+        self._on_error = on_error
+
+    def __call__(self, *args, **kwargs) -> Any:
+        raise NotImplementedError("Not implemented in base class")
+
+    @property
+    def deadline(self) -> float | None:
+        """
+        DEPRECATED: use ``timeout`` instead.  Refer to the ``Retry`` class
+        documentation for details.
+        """
+        return self._timeout
+
+    @property
+    def timeout(self) -> float | None:
+        return self._timeout
+
+    def with_deadline(self, deadline: float | None) -> Self:
+        """Return a copy of this retry with the given timeout.
+
+        DEPRECATED: use :meth:`with_timeout` instead. Refer to the ``Retry`` class
+        documentation for details.
+
+        Args:
+            deadline (float|None): How long to keep retrying, in seconds. If None,
+                no timeout is enforced.
+
+        Returns:
+            Retry: A new retry instance with the given timeout.
+        """
+        return self.with_timeout(deadline)
+
+    def with_timeout(self, timeout: float | None) -> Self:
+        """Return a copy of this retry with the given timeout.
+
+        Args:
+            timeout (float): How long to keep retrying, in seconds. If None,
+                no timeout will be enforced.
+
+        Returns:
+            Retry: A new retry instance with the given timeout.
+        """
+        return type(self)(
+            predicate=self._predicate,
+            initial=self._initial,
+            maximum=self._maximum,
+            multiplier=self._multiplier,
+            timeout=timeout,
+            on_error=self._on_error,
+        )
+
+    def with_predicate(self, predicate: Callable[[Exception], bool]) -> Self:
+        """Return a copy of this retry with the given predicate.
+
+        Args:
+            predicate (Callable[Exception]): A callable that should return
+                ``True`` if the given exception is retryable.
+
+        Returns:
+            Retry: A new retry instance with the given predicate.
+        """
+        return type(self)(
+            predicate=predicate,
+            initial=self._initial,
+            maximum=self._maximum,
+            multiplier=self._multiplier,
+            timeout=self._timeout,
+            on_error=self._on_error,
+        )
+
+    def with_delay(
+        self,
+        initial: Optional[float] = None,
+        maximum: Optional[float] = None,
+        multiplier: Optional[float] = None,
+    ) -> Self:
+        """Return a copy of this retry with the given delay options.
+
+        Args:
+            initial (float): The minimum amount of time to delay (in seconds). This must
+                be greater than 0. If None, the current value is used.
+            maximum (float): The maximum amount of time to delay (in seconds). If None, the
+                current value is used.
+            multiplier (float): The multiplier applied to the delay. If None, the current
+                value is used.
+
+        Returns:
+            Retry: A new retry instance with the given delay options.
+        """
+        return type(self)(
+            predicate=self._predicate,
+            initial=initial if initial is not None else self._initial,
+            maximum=maximum if maximum is not None else self._maximum,
+            multiplier=multiplier if multiplier is not None else self._multiplier,
+            timeout=self._timeout,
+            on_error=self._on_error,
+        )
+
+    def __str__(self) -> str:
+        return (
+            "<{} predicate={}, initial={:.1f}, maximum={:.1f}, "
+            "multiplier={:.1f}, timeout={}, on_error={}>".format(
+                type(self).__name__,
+                self._predicate,
+                self._initial,
+                self._maximum,
+                self._multiplier,
+                self._timeout,  # timeout can be None, thus no {:.1f}
+                self._on_error,
+            )
+        )
diff --git a/google/api_core/retry/retry_streaming.py b/google/api_core/retry/retry_streaming.py
new file mode 100644
index 00000000..e4474c8a
--- /dev/null
+++ b/google/api_core/retry/retry_streaming.py
@@ -0,0 +1,264 @@
+# Copyright 2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Generator wrapper for retryable streaming RPCs.
+"""
+from __future__ import annotations
+
+from typing import (
+    Callable,
+    Optional,
+    List,
+    Tuple,
+    Iterable,
+    Generator,
+    TypeVar,
+    Any,
+    TYPE_CHECKING,
+)
+
+import sys
+import time
+import functools
+
+from google.api_core.retry.retry_base import _BaseRetry
+from google.api_core.retry.retry_base import _retry_error_helper
+from google.api_core.retry import exponential_sleep_generator
+from google.api_core.retry import build_retry_error
+from google.api_core.retry import RetryFailureReason
+
+if TYPE_CHECKING:
+    if sys.version_info >= (3, 10):
+        from typing import ParamSpec
+    else:
+        from typing_extensions import ParamSpec
+
+    _P = ParamSpec("_P")  # target function call parameters
+    _Y = TypeVar("_Y")  # yielded values
+
+
+def retry_target_stream(
+    target: Callable[_P, Iterable[_Y]],
+    predicate: Callable[[Exception], bool],
+    sleep_generator: Iterable[float],
+    timeout: Optional[float] = None,
+    on_error: Optional[Callable[[Exception], None]] = None,
+    exception_factory: Callable[
+        [List[Exception], RetryFailureReason, Optional[float]],
+        Tuple[Exception, Optional[Exception]],
+    ] = build_retry_error,
+    init_args: tuple = (),
+    init_kwargs: dict = {},
+    **kwargs,
+) -> Generator[_Y, Any, None]:
+    """Create a generator wrapper that retries the wrapped stream if it fails.
+
+    This is the lowest-level retry helper. Generally, you'll use the
+    higher-level retry helper :class:`Retry`.
+
+    Args:
+        target: The generator function to call and retry.
+        predicate: A callable used to determine if an
+            exception raised by the target should be considered retryable.
+            It should return True to retry or False otherwise.
+        sleep_generator: An infinite iterator that determines
+            how long to sleep between retries.
+        timeout: How long to keep retrying the target.
+            Note: timeout is only checked before initiating a retry, so the target may
+            run past the timeout value as long as it is healthy.
+        on_error: If given, the on_error callback will be called with each
+            retryable exception raised by the target. Any error raised by this
+            function will *not* be caught.
+        exception_factory: A function that is called when the retryable reaches
+            a terminal failure state, used to construct an exception to be raised.
+            It takes a list of all exceptions encountered, a retry.RetryFailureReason
+            enum indicating the failure cause, and the original timeout value
+            as arguments. It should return a tuple of the exception to be raised,
+            along with the cause exception if any. The default implementation will raise
+            a RetryError on timeout, or the last exception encountered otherwise.
+        init_args: Positional arguments to pass to the target function.
+        init_kwargs: Keyword arguments to pass to the target function.
+
+    Returns:
+        Generator: A retryable generator that wraps the target generator function.
+
+    Raises:
+        ValueError: If the sleep generator stops yielding values.
+        Exception: a custom exception specified by the exception_factory if provided.
+            If no exception_factory is provided:
+                google.api_core.RetryError: If the timeout is exceeded while retrying.
+                Exception: If the target raises an error that isn't retryable.
+    """
+
+    timeout = kwargs.get("deadline", timeout)
+    deadline: Optional[float] = (
+        time.monotonic() + timeout if timeout is not None else None
+    )
+    error_list: list[Exception] = []
+    sleep_iter = iter(sleep_generator)
+
+    # continue trying until an attempt completes, or a terminal exception is raised in _retry_error_helper
+    # TODO: support max_attempts argument: https://github.com/googleapis/python-api-core/issues/535
+    while True:
+        # Start a new retry loop
+        try:
+            # Note: in the future, we can add a ResumptionStrategy object
+            # to generate new args between calls. For now, use the same args
+            # for each attempt.
+            subgenerator = target(*init_args, **init_kwargs)
+            return (yield from subgenerator)
+        # handle exceptions raised by the subgenerator
+        # pylint: disable=broad-except
+        # This function explicitly must deal with broad exceptions.
+        except Exception as exc:
+            # defer to shared logic for handling errors
+            next_sleep = _retry_error_helper(
+                exc,
+                deadline,
+                sleep_iter,
+                error_list,
+                predicate,
+                on_error,
+                exception_factory,
+                timeout,
+            )
+            # if exception not raised, sleep before next attempt
+            time.sleep(next_sleep)
+
+
+class StreamingRetry(_BaseRetry):
+    """Exponential retry decorator for streaming synchronous RPCs.
+
+    This class returns a Generator when called, which wraps the target
+    stream in retry logic. If any exception is raised by the target, the
+    entire stream will be retried within the wrapper.
+
+    Although the default behavior is to retry transient API errors, a
+    different predicate can be provided to retry other exceptions.
+
+    Important Note: when a stream encounters a retryable error, it will
+    silently construct a fresh iterator instance in the background
+    and continue yielding (likely duplicate) values as if no error occurred.
+    This is the most general way to retry a stream, but it often is not the
+    desired behavior. Example: iter([1, 2, 1/0]) -> [1, 2, 1, 2, ...]
+
+    There are two ways to build more advanced retry logic for streams:
+
+    1. Wrap the target
+        Use a ``target`` that maintains state between retries, and creates a
+        different generator on each retry call. For example, you can wrap a
+        network call in a function that modifies the request based on what has
+        already been returned:
+
+        .. code-block:: python
+
+            def attempt_with_modified_request(target, request, seen_items=[]):
+                # remove seen items from request on each attempt
+                new_request = modify_request(request, seen_items)
+                new_generator = target(new_request)
+                for item in new_generator:
+                    yield item
+                    seen_items.append(item)
+
+            retry_wrapped_fn = StreamingRetry()(attempt_with_modified_request)
+            retryable_generator = retry_wrapped_fn(target, request)
+
+    2. Wrap the retry generator
+        Alternatively, you can wrap the retryable generator itself before
+        passing it to the end-user to add a filter on the stream. For
+        example, you can keep track of the items that were successfully yielded
+        in previous retry attempts, and only yield new items when the
+        new attempt surpasses the previous ones:
+
+        .. code-block:: python
+
+            def retryable_with_filter(target):
+                stream_idx = 0
+                # reset stream_idx when the stream is retried
+                def on_error(e):
+                    nonlocal stream_idx
+                    stream_idx = 0
+                # build retryable
+                retryable_gen = StreamingRetry(...)(target)
+                # keep track of what has been yielded out of filter
+                seen_items = []
+                for item in retryable_gen():
+                    if stream_idx >= len(seen_items):
+                        seen_items.append(item)
+                        yield item
+                    elif item != seen_items[stream_idx]:
+                        raise ValueError("Stream differs from last attempt")
+                    stream_idx += 1
+
+            filter_retry_wrapped = retryable_with_filter(target)
+
+    Args:
+        predicate (Callable[Exception]): A callable that should return ``True``
+            if the given exception is retryable.
+        initial (float): The minimum amount of time to delay in seconds. This
+            must be greater than 0.
+        maximum (float): The maximum amount of time to delay in seconds.
+        multiplier (float): The multiplier applied to the delay.
+        timeout (float): How long to keep retrying, in seconds.
+            Note: timeout is only checked before initiating a retry, so the target may
+            run past the timeout value as long as it is healthy.
+        on_error (Callable[Exception]): A function to call while processing
+            a retryable exception. Any error raised by this function will
+            *not* be caught.
+        deadline (float): DEPRECATED: use `timeout` instead. For backward
+            compatibility, if specified it will override the ``timeout`` parameter.
+    """
+
+    def __call__(
+        self,
+        func: Callable[_P, Iterable[_Y]],
+        on_error: Callable[[Exception], Any] | None = None,
+    ) -> Callable[_P, Generator[_Y, Any, None]]:
+        """Wrap a callable with retry behavior.
+
+        Args:
+            func (Callable): The callable to add retry behavior to.
+            on_error (Optional[Callable[Exception]]): If given, the
+                on_error callback will be called with each retryable exception
+                raised by the wrapped function. Any error raised by this
+                function will *not* be caught. If on_error was specified in the
+                constructor, this value will be ignored.
+
+        Returns:
+            Callable: A callable that will invoke ``func`` with retry
+                behavior.
+        """
+        if self._on_error is not None:
+            on_error = self._on_error
+
+        @functools.wraps(func)
+        def retry_wrapped_func(
+            *args: _P.args, **kwargs: _P.kwargs
+        ) -> Generator[_Y, Any, None]:
+            """A wrapper that calls target function with retry."""
+            sleep_generator = exponential_sleep_generator(
+                self._initial, self._maximum, multiplier=self._multiplier
+            )
+            return retry_target_stream(
+                func,
+                predicate=self._predicate,
+                sleep_generator=sleep_generator,
+                timeout=self._timeout,
+                on_error=on_error,
+                init_args=args,
+                init_kwargs=kwargs,
+            )
+
+        return retry_wrapped_func
diff --git a/google/api_core/retry/retry_streaming_async.py b/google/api_core/retry/retry_streaming_async.py
new file mode 100644
index 00000000..5e5fa240
--- /dev/null
+++ b/google/api_core/retry/retry_streaming_async.py
@@ -0,0 +1,328 @@
+# Copyright 2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Generator wrapper for retryable async streaming RPCs.
+"""
+from __future__ import annotations
+
+from typing import (
+    cast,
+    Any,
+    Callable,
+    Iterable,
+    AsyncIterator,
+    AsyncIterable,
+    Awaitable,
+    TypeVar,
+    AsyncGenerator,
+    TYPE_CHECKING,
+)
+
+import asyncio
+import time
+import sys
+import functools
+
+from google.api_core.retry.retry_base import _BaseRetry
+from google.api_core.retry.retry_base import _retry_error_helper
+from google.api_core.retry import exponential_sleep_generator
+from google.api_core.retry import build_retry_error
+from google.api_core.retry import RetryFailureReason
+
+
+if TYPE_CHECKING:
+    if sys.version_info >= (3, 10):
+        from typing import ParamSpec
+    else:
+        from typing_extensions import ParamSpec
+
+    _P = ParamSpec("_P")  # target function call parameters
+    _Y = TypeVar("_Y")  # yielded values
+
+
+async def retry_target_stream(
+    target: Callable[_P, AsyncIterable[_Y] | Awaitable[AsyncIterable[_Y]]],
+    predicate: Callable[[Exception], bool],
+    sleep_generator: Iterable[float],
+    timeout: float | None = None,
+    on_error: Callable[[Exception], None] | None = None,
+    exception_factory: Callable[
+        [list[Exception], RetryFailureReason, float | None],
+        tuple[Exception, Exception | None],
+    ] = build_retry_error,
+    init_args: tuple = (),
+    init_kwargs: dict = {},
+    **kwargs,
+) -> AsyncGenerator[_Y, None]:
+    """Create a generator wrapper that retries the wrapped stream if it fails.
+
+    This is the lowest-level retry helper. Generally, you'll use the
+    higher-level retry helper :class:`AsyncRetry`.
+
+    Args:
+        target: The generator function to call and retry.
+        predicate: A callable used to determine if an
+            exception raised by the target should be considered retryable.
+            It should return True to retry or False otherwise.
+        sleep_generator: An infinite iterator that determines
+            how long to sleep between retries.
+        timeout: How long to keep retrying the target.
+            Note: timeout is only checked before initiating a retry, so the target may
+            run past the timeout value as long as it is healthy.
+        on_error: If given, the on_error callback will be called with each
+            retryable exception raised by the target. Any error raised by this
+            function will *not* be caught.
+        exception_factory: A function that is called when the retryable reaches
+            a terminal failure state, used to construct an exception to be raised.
+            It takes a list of all exceptions encountered, a retry.RetryFailureReason
+            enum indicating the failure cause, and the original timeout value
+            as arguments. It should return a tuple of the exception to be raised,
+            along with the cause exception if any. The default implementation will raise
+            a RetryError on timeout, or the last exception encountered otherwise.
+        init_args: Positional arguments to pass to the target function.
+        init_kwargs: Keyword arguments to pass to the target function.
+
+    Returns:
+        AsyncGenerator: A retryable generator that wraps the target generator function.
+
+    Raises:
+        ValueError: If the sleep generator stops yielding values.
+        Exception: a custom exception specified by the exception_factory if provided.
+            If no exception_factory is provided:
+                google.api_core.RetryError: If the timeout is exceeded while retrying.
+                Exception: If the target raises an error that isn't retryable.
+    """
+    target_iterator: AsyncIterator[_Y] | None = None
+    timeout = kwargs.get("deadline", timeout)
+    deadline = time.monotonic() + timeout if timeout else None
+    # keep track of retryable exceptions we encounter to pass in to exception_factory
+    error_list: list[Exception] = []
+    sleep_iter = iter(sleep_generator)
+    target_is_generator: bool | None = None
+
+    # continue trying until an attempt completes, or a terminal exception is raised in _retry_error_helper
+    # TODO: support max_attempts argument: https://github.com/googleapis/python-api-core/issues/535
+    while True:
+        # Start a new retry loop
+        try:
+            # Note: in the future, we can add a ResumptionStrategy object
+            # to generate new args between calls. For now, use the same args
+            # for each attempt.
+            target_output: AsyncIterable[_Y] | Awaitable[AsyncIterable[_Y]] = target(
+                *init_args, **init_kwargs
+            )
+            try:
+                # gapic functions return the generator behind an awaitable
+                # unwrap the awaitable so we can work with the generator directly
+                target_output = await target_output  # type: ignore
+            except TypeError:
+                # was not awaitable, continue
+                pass
+            target_iterator = cast(AsyncIterable["_Y"], target_output).__aiter__()
+
+            if target_is_generator is None:
+                # Check if target supports generator features (asend, athrow, aclose)
+                target_is_generator = bool(getattr(target_iterator, "asend", None))
+
+            sent_in = None
+            while True:
+                ## Read from target_iterator
+                # If the target is a generator, we will advance it with `asend`
+                # otherwise, we will use `anext`
+                if target_is_generator:
+                    next_value = await target_iterator.asend(sent_in)  # type: ignore
+                else:
+                    next_value = await target_iterator.__anext__()
+                ## Yield from Wrapper to caller
+                try:
+                    # yield latest value from target
+                    # exceptions from `athrow` and `aclose` are injected here
+                    sent_in = yield next_value
+                except GeneratorExit:
+                    # if wrapper received `aclose` while waiting on yield,
+                    # it will raise GeneratorExit here
+                    if target_is_generator:
+                        # pass to inner target_iterator for handling
+                        await cast(AsyncGenerator["_Y", None], target_iterator).aclose()
+                    else:
+                        raise
+                    return
+                except:  # noqa: E722
+                    # bare except catches any exception passed to `athrow`
+                    if target_is_generator:
+                        # delegate error handling to target_iterator
+                        await cast(AsyncGenerator["_Y", None], target_iterator).athrow(
+                            cast(BaseException, sys.exc_info()[1])
+                        )
+                    else:
+                        raise
+            return
+        except StopAsyncIteration:
+            # if iterator exhausted, return
+            return
+        # handle exceptions raised by the target_iterator
+        # pylint: disable=broad-except
+        # This function explicitly must deal with broad exceptions.
+        except Exception as exc:
+            # defer to shared logic for handling errors
+            next_sleep = _retry_error_helper(
+                exc,
+                deadline,
+                sleep_iter,
+                error_list,
+                predicate,
+                on_error,
+                exception_factory,
+                timeout,
+            )
+            # if exception not raised, sleep before next attempt
+            await asyncio.sleep(next_sleep)
+
+        finally:
+            if target_is_generator and target_iterator is not None:
+                await cast(AsyncGenerator["_Y", None], target_iterator).aclose()
+
+
+class AsyncStreamingRetry(_BaseRetry):
+    """Exponential retry decorator for async streaming rpcs.
+
+    This class returns an AsyncGenerator when called, which wraps the target
+    stream in retry logic. If any exception is raised by the target, the
+    entire stream will be retried within the wrapper.
+
+    Although the default behavior is to retry transient API errors, a
+    different predicate can be provided to retry other exceptions.
+
+    Important Note: when a stream is encounters a retryable error, it will
+    silently construct a fresh iterator instance in the background
+    and continue yielding (likely duplicate) values as if no error occurred.
+    This is the most general way to retry a stream, but it often is not the
+    desired behavior. Example: iter([1, 2, 1/0]) -> [1, 2, 1, 2, ...]
+
+    There are two ways to build more advanced retry logic for streams:
+
+    1. Wrap the target
+        Use a ``target`` that maintains state between retries, and creates a
+        different generator on each retry call. For example, you can wrap a
+        grpc call in a function that modifies the request based on what has
+        already been returned:
+
+        .. code-block:: python
+
+            async def attempt_with_modified_request(target, request, seen_items=[]):
+                # remove seen items from request on each attempt
+                new_request = modify_request(request, seen_items)
+                new_generator = await target(new_request)
+                async for item in new_generator:
+                    yield item
+                    seen_items.append(item)
+
+            retry_wrapped = AsyncRetry(is_stream=True,...)(attempt_with_modified_request, target, request, [])
+
+        2. Wrap the retry generator
+            Alternatively, you can wrap the retryable generator itself before
+            passing it to the end-user to add a filter on the stream. For
+            example, you can keep track of the items that were successfully yielded
+            in previous retry attempts, and only yield new items when the
+            new attempt surpasses the previous ones:
+
+            .. code-block:: python
+
+                async def retryable_with_filter(target):
+                    stream_idx = 0
+                    # reset stream_idx when the stream is retried
+                    def on_error(e):
+                        nonlocal stream_idx
+                        stream_idx = 0
+                    # build retryable
+                    retryable_gen = AsyncRetry(is_stream=True, ...)(target)
+                    # keep track of what has been yielded out of filter
+                    seen_items = []
+                    async for item in retryable_gen:
+                        if stream_idx >= len(seen_items):
+                            yield item
+                            seen_items.append(item)
+                        elif item != previous_stream[stream_idx]:
+                            raise ValueError("Stream differs from last attempt")"
+                        stream_idx += 1
+
+                filter_retry_wrapped = retryable_with_filter(target)
+
+    Args:
+        predicate (Callable[Exception]): A callable that should return ``True``
+            if the given exception is retryable.
+        initial (float): The minimum amount of time to delay in seconds. This
+            must be greater than 0.
+        maximum (float): The maximum amount of time to delay in seconds.
+        multiplier (float): The multiplier applied to the delay.
+        timeout (Optional[float]): How long to keep retrying in seconds.
+            Note: timeout is only checked before initiating a retry, so the target may
+            run past the timeout value as long as it is healthy.
+        on_error (Optional[Callable[Exception]]): A function to call while processing
+            a retryable exception. Any error raised by this function will
+            *not* be caught.
+        is_stream (bool): Indicates whether the input function
+            should be treated as a stream function (i.e. an AsyncGenerator,
+            or function or coroutine that returns an AsyncIterable).
+            If True, the iterable will be wrapped with retry logic, and any
+            failed outputs will restart the stream. If False, only the input
+            function call itself will be retried. Defaults to False.
+            To avoid duplicate values, retryable streams should typically be
+            wrapped in additional filter logic before use.
+        deadline (float): DEPRECATED use ``timeout`` instead. If set it will
+        override ``timeout`` parameter.
+    """
+
+    def __call__(
+        self,
+        func: Callable[..., AsyncIterable[_Y] | Awaitable[AsyncIterable[_Y]]],
+        on_error: Callable[[Exception], Any] | None = None,
+    ) -> Callable[_P, Awaitable[AsyncGenerator[_Y, None]]]:
+        """Wrap a callable with retry behavior.
+
+        Args:
+            func (Callable): The callable or stream to add retry behavior to.
+            on_error (Optional[Callable[Exception]]): If given, the
+                on_error callback will be called with each retryable exception
+                raised by the wrapped function. Any error raised by this
+                function will *not* be caught. If on_error was specified in the
+                constructor, this value will be ignored.
+
+        Returns:
+            Callable: A callable that will invoke ``func`` with retry
+                behavior.
+        """
+        if self._on_error is not None:
+            on_error = self._on_error
+
+        @functools.wraps(func)
+        async def retry_wrapped_func(
+            *args: _P.args, **kwargs: _P.kwargs
+        ) -> AsyncGenerator[_Y, None]:
+            """A wrapper that calls target function with retry."""
+            sleep_generator = exponential_sleep_generator(
+                self._initial, self._maximum, multiplier=self._multiplier
+            )
+            return retry_target_stream(
+                func,
+                self._predicate,
+                sleep_generator,
+                self._timeout,
+                on_error,
+                init_args=args,
+                init_kwargs=kwargs,
+            )
+
+        return retry_wrapped_func
diff --git a/google/api_core/retry/retry_unary.py b/google/api_core/retry/retry_unary.py
new file mode 100644
index 00000000..6d36bc7d
--- /dev/null
+++ b/google/api_core/retry/retry_unary.py
@@ -0,0 +1,302 @@
+# Copyright 2017 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helpers for retrying functions with exponential back-off.
+
+The :class:`Retry` decorator can be used to retry functions that raise
+exceptions using exponential backoff. Because a exponential sleep algorithm is
+used, the retry is limited by a `timeout`. The timeout determines the window
+in which retries will be attempted. This is used instead of total number of retries
+because it is difficult to ascertain the amount of time a function can block
+when using total number of retries and exponential backoff.
+
+By default, this decorator will retry transient
+API errors (see :func:`if_transient_error`). For example:
+
+.. code-block:: python
+
+    @retry.Retry()
+    def call_flaky_rpc():
+        return client.flaky_rpc()
+
+    # Will retry flaky_rpc() if it raises transient API errors.
+    result = call_flaky_rpc()
+
+You can pass a custom predicate to retry on different exceptions, such as
+waiting for an eventually consistent item to be available:
+
+.. code-block:: python
+
+    @retry.Retry(predicate=if_exception_type(exceptions.NotFound))
+    def check_if_exists():
+        return client.does_thing_exist()
+
+    is_available = check_if_exists()
+
+Some client library methods apply retry automatically. These methods can accept
+a ``retry`` parameter that allows you to configure the behavior:
+
+.. code-block:: python
+
+    my_retry = retry.Retry(timeout=60)
+    result = client.some_method(retry=my_retry)
+
+"""
+
+from __future__ import annotations
+
+import functools
+import sys
+import time
+import inspect
+import warnings
+from typing import Any, Callable, Iterable, TypeVar, TYPE_CHECKING
+
+from google.api_core.retry.retry_base import _BaseRetry
+from google.api_core.retry.retry_base import _retry_error_helper
+from google.api_core.retry.retry_base import exponential_sleep_generator
+from google.api_core.retry.retry_base import build_retry_error
+from google.api_core.retry.retry_base import RetryFailureReason
+
+
+if TYPE_CHECKING:
+    if sys.version_info >= (3, 10):
+        from typing import ParamSpec
+    else:
+        from typing_extensions import ParamSpec
+
+    _P = ParamSpec("_P")  # target function call parameters
+    _R = TypeVar("_R")  # target function returned value
+
+_ASYNC_RETRY_WARNING = "Using the synchronous google.api_core.retry.Retry with asynchronous calls may lead to unexpected results. Please use google.api_core.retry_async.AsyncRetry instead."
+
+
+def retry_target(
+    target: Callable[[], _R],
+    predicate: Callable[[Exception], bool],
+    sleep_generator: Iterable[float],
+    timeout: float | None = None,
+    on_error: Callable[[Exception], None] | None = None,
+    exception_factory: Callable[
+        [list[Exception], RetryFailureReason, float | None],
+        tuple[Exception, Exception | None],
+    ] = build_retry_error,
+    **kwargs,
+):
+    """Call a function and retry if it fails.
+
+    This is the lowest-level retry helper. Generally, you'll use the
+    higher-level retry helper :class:`Retry`.
+
+    Args:
+        target(Callable): The function to call and retry. This must be a
+            nullary function - apply arguments with `functools.partial`.
+        predicate (Callable[Exception]): A callable used to determine if an
+            exception raised by the target should be considered retryable.
+            It should return True to retry or False otherwise.
+        sleep_generator (Iterable[float]): An infinite iterator that determines
+            how long to sleep between retries.
+        timeout (Optional[float]): How long to keep retrying the target.
+            Note: timeout is only checked before initiating a retry, so the target may
+            run past the timeout value as long as it is healthy.
+        on_error (Optional[Callable[Exception]]): If given, the on_error
+            callback will be called with each retryable exception raised by the
+            target. Any error raised by this function will *not* be caught.
+        exception_factory: A function that is called when the retryable reaches
+            a terminal failure state, used to construct an exception to be raised.
+            It takes a list of all exceptions encountered, a retry.RetryFailureReason
+            enum indicating the failure cause, and the original timeout value
+            as arguments. It should return a tuple of the exception to be raised,
+            along with the cause exception if any. The default implementation will raise
+            a RetryError on timeout, or the last exception encountered otherwise.
+        deadline (float): DEPRECATED: use ``timeout`` instead. For backward
+            compatibility, if specified it will override ``timeout`` parameter.
+
+    Returns:
+        Any: the return value of the target function.
+
+    Raises:
+        ValueError: If the sleep generator stops yielding values.
+        Exception: a custom exception specified by the exception_factory if provided.
+            If no exception_factory is provided:
+                google.api_core.RetryError: If the timeout is exceeded while retrying.
+                Exception: If the target raises an error that isn't retryable.
+    """
+
+    timeout = kwargs.get("deadline", timeout)
+
+    deadline = time.monotonic() + timeout if timeout is not None else None
+    error_list: list[Exception] = []
+    sleep_iter = iter(sleep_generator)
+
+    # continue trying until an attempt completes, or a terminal exception is raised in _retry_error_helper
+    # TODO: support max_attempts argument: https://github.com/googleapis/python-api-core/issues/535
+    while True:
+        try:
+            result = target()
+            if inspect.isawaitable(result):
+                warnings.warn(_ASYNC_RETRY_WARNING)
+            return result
+
+        # pylint: disable=broad-except
+        # This function explicitly must deal with broad exceptions.
+        except Exception as exc:
+            # defer to shared logic for handling errors
+            next_sleep = _retry_error_helper(
+                exc,
+                deadline,
+                sleep_iter,
+                error_list,
+                predicate,
+                on_error,
+                exception_factory,
+                timeout,
+            )
+            # if exception not raised, sleep before next attempt
+            time.sleep(next_sleep)
+
+
+class Retry(_BaseRetry):
+    """Exponential retry decorator for unary synchronous RPCs.
+
+    This class is a decorator used to add retry or polling behavior to an RPC
+    call.
+
+    Although the default behavior is to retry transient API errors, a
+    different predicate can be provided to retry other exceptions.
+
+    There are two important concepts that retry/polling behavior may operate on,
+    Deadline and Timeout, which need to be properly defined for the correct
+    usage of this class and the rest of the library.
+
+    Deadline: a fixed point in time by which a certain operation must
+    terminate. For example, if a certain operation has a deadline
+    "2022-10-18T23:30:52.123Z" it must terminate (successfully or with an
+    error) by that time, regardless of when it was started or whether it
+    was started at all.
+
+    Timeout: the maximum duration of time after which a certain operation
+    must terminate (successfully or with an error). The countdown begins right
+    after an operation was started. For example, if an operation was started at
+    09:24:00 with timeout of 75 seconds, it must terminate no later than
+    09:25:15.
+
+    Unfortunately, in the past this class (and the api-core library as a whole) has not
+    been properly distinguishing the concepts of "timeout" and "deadline", and the
+    ``deadline`` parameter has meant ``timeout``. That is why
+    ``deadline`` has been deprecated and ``timeout`` should be used instead. If the
+    ``deadline`` parameter is set, it will override the ``timeout`` parameter.
+    In other words, ``retry.deadline`` should be treated as just a deprecated alias for
+    ``retry.timeout``.
+
+    Said another way, it is safe to assume that this class and the rest of this
+    library operate in terms of timeouts (not deadlines) unless explicitly
+    noted the usage of deadline semantics.
+
+    It is also important to
+    understand the three most common applications of the Timeout concept in the
+    context of this library.
+
+    Usually the generic Timeout term may stand for one of the following actual
+    timeouts: RPC Timeout, Retry Timeout, or Polling Timeout.
+
+    RPC Timeout: a value supplied by the client to the server so
+    that the server side knows the maximum amount of time it is expected to
+    spend handling that specific RPC. For example, in the case of gRPC transport,
+    RPC Timeout is represented by setting "grpc-timeout" header in the HTTP2
+    request. The `timeout` property of this class normally never represents the
+    RPC Timeout as it is handled separately by the ``google.api_core.timeout``
+    module of this library.
+
+    Retry Timeout: this is the most common meaning of the ``timeout`` property
+    of this class, and defines how long a certain RPC may be retried in case
+    the server returns an error.
+
+    Polling Timeout: defines how long the
+    client side is allowed to call the polling RPC repeatedly to check a status of a
+    long-running operation. Each polling RPC is
+    expected to succeed (its errors are supposed to be handled by the retry
+    logic). The decision as to whether a new polling attempt needs to be made is based
+    not on the RPC status code but  on the status of the returned
+    status of an operation. In other words: we will poll a long-running operation until
+    the operation is done or the polling timeout expires. Each poll will inform us of
+    the status of the operation. The poll consists of an RPC to the server that may
+    itself be retried as per the poll-specific retry settings in case of errors. The
+    operation-level retry settings do NOT apply to polling-RPC retries.
+
+    With the actual timeout types being defined above, the client libraries
+    often refer to just Timeout without clarifying which type specifically
+    that is. In that case the actual timeout type (sometimes also referred to as
+    Logical Timeout) can be determined from the context. If it is a unary rpc
+    call (i.e. a regular one) Timeout usually stands for the RPC Timeout (if
+    provided directly as a standalone value) or Retry Timeout (if provided as
+    ``retry.timeout`` property of the unary RPC's retry config). For
+    ``Operation`` or ``PollingFuture`` in general Timeout stands for
+    Polling Timeout.
+
+    Args:
+        predicate (Callable[Exception]): A callable that should return ``True``
+            if the given exception is retryable.
+        initial (float): The minimum amount of time to delay in seconds. This
+            must be greater than 0.
+        maximum (float): The maximum amount of time to delay in seconds.
+        multiplier (float): The multiplier applied to the delay.
+        timeout (Optional[float]): How long to keep retrying, in seconds.
+            Note: timeout is only checked before initiating a retry, so the target may
+            run past the timeout value as long as it is healthy.
+        on_error (Callable[Exception]): A function to call while processing
+            a retryable exception. Any error raised by this function will
+            *not* be caught.
+        deadline (float): DEPRECATED: use `timeout` instead. For backward
+            compatibility, if specified it will override the ``timeout`` parameter.
+    """
+
+    def __call__(
+        self,
+        func: Callable[_P, _R],
+        on_error: Callable[[Exception], Any] | None = None,
+    ) -> Callable[_P, _R]:
+        """Wrap a callable with retry behavior.
+
+        Args:
+            func (Callable): The callable to add retry behavior to.
+            on_error (Optional[Callable[Exception]]): If given, the
+                on_error callback will be called with each retryable exception
+                raised by the wrapped function. Any error raised by this
+                function will *not* be caught. If on_error was specified in the
+                constructor, this value will be ignored.
+
+        Returns:
+            Callable: A callable that will invoke ``func`` with retry
+                behavior.
+        """
+        if self._on_error is not None:
+            on_error = self._on_error
+
+        @functools.wraps(func)
+        def retry_wrapped_func(*args: _P.args, **kwargs: _P.kwargs) -> _R:
+            """A wrapper that calls target function with retry."""
+            target = functools.partial(func, *args, **kwargs)
+            sleep_generator = exponential_sleep_generator(
+                self._initial, self._maximum, multiplier=self._multiplier
+            )
+            return retry_target(
+                target,
+                self._predicate,
+                sleep_generator,
+                timeout=self._timeout,
+                on_error=on_error,
+            )
+
+        return retry_wrapped_func
diff --git a/google/api_core/retry/retry_unary_async.py b/google/api_core/retry/retry_unary_async.py
new file mode 100644
index 00000000..1f72476a
--- /dev/null
+++ b/google/api_core/retry/retry_unary_async.py
@@ -0,0 +1,239 @@
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helpers for retrying coroutine functions with exponential back-off.
+
+The :class:`AsyncRetry` decorator shares most functionality and behavior with
+:class:`Retry`, but supports coroutine functions. Please refer to description
+of :class:`Retry` for more details.
+
+By default, this decorator will retry transient
+API errors (see :func:`if_transient_error`). For example:
+
+.. code-block:: python
+
+    @retry_async.AsyncRetry()
+    async def call_flaky_rpc():
+        return await client.flaky_rpc()
+
+    # Will retry flaky_rpc() if it raises transient API errors.
+    result = await call_flaky_rpc()
+
+You can pass a custom predicate to retry on different exceptions, such as
+waiting for an eventually consistent item to be available:
+
+.. code-block:: python
+
+    @retry_async.AsyncRetry(predicate=retry_async.if_exception_type(exceptions.NotFound))
+    async def check_if_exists():
+        return await client.does_thing_exist()
+
+    is_available = await check_if_exists()
+
+Some client library methods apply retry automatically. These methods can accept
+a ``retry`` parameter that allows you to configure the behavior:
+
+.. code-block:: python
+
+    my_retry = retry_async.AsyncRetry(timeout=60)
+    result = await client.some_method(retry=my_retry)
+
+"""
+
+from __future__ import annotations
+
+import asyncio
+import time
+import functools
+from typing import (
+    Awaitable,
+    Any,
+    Callable,
+    Iterable,
+    TypeVar,
+    TYPE_CHECKING,
+)
+
+from google.api_core.retry.retry_base import _BaseRetry
+from google.api_core.retry.retry_base import _retry_error_helper
+from google.api_core.retry.retry_base import exponential_sleep_generator
+from google.api_core.retry.retry_base import build_retry_error
+from google.api_core.retry.retry_base import RetryFailureReason
+
+# for backwards compatibility, expose helpers in this module
+from google.api_core.retry.retry_base import if_exception_type  # noqa
+from google.api_core.retry.retry_base import if_transient_error  # noqa
+
+if TYPE_CHECKING:
+    import sys
+
+    if sys.version_info >= (3, 10):
+        from typing import ParamSpec
+    else:
+        from typing_extensions import ParamSpec
+
+    _P = ParamSpec("_P")  # target function call parameters
+    _R = TypeVar("_R")  # target function returned value
+
+_DEFAULT_INITIAL_DELAY = 1.0  # seconds
+_DEFAULT_MAXIMUM_DELAY = 60.0  # seconds
+_DEFAULT_DELAY_MULTIPLIER = 2.0
+_DEFAULT_DEADLINE = 60.0 * 2.0  # seconds
+_DEFAULT_TIMEOUT = 60.0 * 2.0  # seconds
+
+
+async def retry_target(
+    target: Callable[[], Awaitable[_R]],
+    predicate: Callable[[Exception], bool],
+    sleep_generator: Iterable[float],
+    timeout: float | None = None,
+    on_error: Callable[[Exception], None] | None = None,
+    exception_factory: Callable[
+        [list[Exception], RetryFailureReason, float | None],
+        tuple[Exception, Exception | None],
+    ] = build_retry_error,
+    **kwargs,
+):
+    """Await a coroutine and retry if it fails.
+
+    This is the lowest-level retry helper. Generally, you'll use the
+    higher-level retry helper :class:`Retry`.
+
+    Args:
+        target(Callable[[], Any]): The function to call and retry. This must be a
+            nullary function - apply arguments with `functools.partial`.
+        predicate (Callable[Exception]): A callable used to determine if an
+            exception raised by the target should be considered retryable.
+            It should return True to retry or False otherwise.
+        sleep_generator (Iterable[float]): An infinite iterator that determines
+            how long to sleep between retries.
+        timeout (Optional[float]): How long to keep retrying the target, in seconds.
+            Note: timeout is only checked before initiating a retry, so the target may
+            run past the timeout value as long as it is healthy.
+        on_error (Optional[Callable[Exception]]): If given, the on_error
+            callback will be called with each retryable exception raised by the
+            target. Any error raised by this function will *not* be caught.
+        exception_factory: A function that is called when the retryable reaches
+            a terminal failure state, used to construct an exception to be raised.
+            It takes a list of all exceptions encountered, a retry.RetryFailureReason
+            enum indicating the failure cause, and the original timeout value
+            as arguments. It should return a tuple of the exception to be raised,
+            along with the cause exception if any. The default implementation will raise
+            a RetryError on timeout, or the last exception encountered otherwise.
+        deadline (float): DEPRECATED use ``timeout`` instead. For backward
+            compatibility, if set it will override the ``timeout`` parameter.
+
+    Returns:
+        Any: the return value of the target function.
+
+    Raises:
+        ValueError: If the sleep generator stops yielding values.
+        Exception: a custom exception specified by the exception_factory if provided.
+            If no exception_factory is provided:
+                google.api_core.RetryError: If the timeout is exceeded while retrying.
+                Exception: If the target raises an error that isn't retryable.
+    """
+
+    timeout = kwargs.get("deadline", timeout)
+
+    deadline = time.monotonic() + timeout if timeout is not None else None
+    error_list: list[Exception] = []
+    sleep_iter = iter(sleep_generator)
+
+    # continue trying until an attempt completes, or a terminal exception is raised in _retry_error_helper
+    # TODO: support max_attempts argument: https://github.com/googleapis/python-api-core/issues/535
+    while True:
+        try:
+            return await target()
+        # pylint: disable=broad-except
+        # This function explicitly must deal with broad exceptions.
+        except Exception as exc:
+            # defer to shared logic for handling errors
+            next_sleep = _retry_error_helper(
+                exc,
+                deadline,
+                sleep_iter,
+                error_list,
+                predicate,
+                on_error,
+                exception_factory,
+                timeout,
+            )
+            # if exception not raised, sleep before next attempt
+            await asyncio.sleep(next_sleep)
+
+
+class AsyncRetry(_BaseRetry):
+    """Exponential retry decorator for async coroutines.
+
+    This class is a decorator used to add exponential back-off retry behavior
+    to an RPC call.
+
+    Although the default behavior is to retry transient API errors, a
+    different predicate can be provided to retry other exceptions.
+
+    Args:
+        predicate (Callable[Exception]): A callable that should return ``True``
+            if the given exception is retryable.
+        initial (float): The minimum amount of time to delay in seconds. This
+            must be greater than 0.
+        maximum (float): The maximum amount of time to delay in seconds.
+        multiplier (float): The multiplier applied to the delay.
+        timeout (Optional[float]): How long to keep retrying in seconds.
+            Note: timeout is only checked before initiating a retry, so the target may
+            run past the timeout value as long as it is healthy.
+        on_error (Optional[Callable[Exception]]): A function to call while processing
+            a retryable exception. Any error raised by this function will
+            *not* be caught.
+        deadline (float): DEPRECATED use ``timeout`` instead. If set it will
+        override ``timeout`` parameter.
+    """
+
+    def __call__(
+        self,
+        func: Callable[..., Awaitable[_R]],
+        on_error: Callable[[Exception], Any] | None = None,
+    ) -> Callable[_P, Awaitable[_R]]:
+        """Wrap a callable with retry behavior.
+
+        Args:
+            func (Callable): The callable or stream to add retry behavior to.
+            on_error (Optional[Callable[Exception]]): If given, the
+                on_error callback will be called with each retryable exception
+                raised by the wrapped function. Any error raised by this
+                function will *not* be caught. If on_error was specified in the
+                constructor, this value will be ignored.
+
+        Returns:
+            Callable: A callable that will invoke ``func`` with retry
+                behavior.
+        """
+        if self._on_error is not None:
+            on_error = self._on_error
+
+        @functools.wraps(func)
+        async def retry_wrapped_func(*args: _P.args, **kwargs: _P.kwargs) -> _R:
+            """A wrapper that calls target function with retry."""
+            sleep_generator = exponential_sleep_generator(
+                self._initial, self._maximum, multiplier=self._multiplier
+            )
+            return await retry_target(
+                functools.partial(func, *args, **kwargs),
+                predicate=self._predicate,
+                sleep_generator=sleep_generator,
+                timeout=self._timeout,
+                on_error=on_error,
+            )
+
+        return retry_wrapped_func
diff --git a/google/api_core/retry_async.py b/google/api_core/retry_async.py
index 2dfa2f6e..90a2d5ad 100644
--- a/google/api_core/retry_async.py
+++ b/google/api_core/retry_async.py
@@ -1,4 +1,4 @@
-# Copyright 2020 Google LLC
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -11,281 +11,24 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-"""Helpers for retrying coroutine functions with exponential back-off.
-
-The :class:`AsyncRetry` decorator shares most functionality and behavior with
-:class:`Retry`, but supports coroutine functions. Please refer to description
-of :class:`Retry` for more details.
-
-By default, this decorator will retry transient
-API errors (see :func:`if_transient_error`). For example:
-
-.. code-block:: python
-
-    @retry_async.AsyncRetry()
-    async def call_flaky_rpc():
-        return await client.flaky_rpc()
-
-    # Will retry flaky_rpc() if it raises transient API errors.
-    result = await call_flaky_rpc()
-
-You can pass a custom predicate to retry on different exceptions, such as
-waiting for an eventually consistent item to be available:
-
-.. code-block:: python
-
-    @retry_async.AsyncRetry(predicate=retry_async.if_exception_type(exceptions.NotFound))
-    async def check_if_exists():
-        return await client.does_thing_exist()
-
-    is_available = await check_if_exists()
-
-Some client library methods apply retry automatically. These methods can accept
-a ``retry`` parameter that allows you to configure the behavior:
-
-.. code-block:: python
-
-    my_retry = retry_async.AsyncRetry(deadline=60)
-    result = await client.some_method(retry=my_retry)
-
-"""
-
-import asyncio
-import datetime
-import functools
-import logging
-
-from google.api_core import datetime_helpers
-from google.api_core import exceptions
-from google.api_core.retry import exponential_sleep_generator
+#
+# The following imports are for backwards compatibility with https://github.com/googleapis/python-api-core/blob/4d7d2edee2c108d43deb151e6e0fdceb56b73275/google/api_core/retry_async.py
+#
+# TODO: Revert these imports on the next major version release (https://github.com/googleapis/python-api-core/issues/576)
+from google.api_core import datetime_helpers  # noqa: F401
+from google.api_core import exceptions  # noqa: F401
+from google.api_core.retry import exponential_sleep_generator  # noqa: F401
 from google.api_core.retry import if_exception_type  # noqa: F401
-from google.api_core.retry import if_transient_error
-
-
-_LOGGER = logging.getLogger(__name__)
-_DEFAULT_INITIAL_DELAY = 1.0  # seconds
-_DEFAULT_MAXIMUM_DELAY = 60.0  # seconds
-_DEFAULT_DELAY_MULTIPLIER = 2.0
-_DEFAULT_DEADLINE = 60.0 * 2.0  # seconds
-
-
-async def retry_target(target, predicate, sleep_generator, deadline, on_error=None):
-    """Call a function and retry if it fails.
-
-    This is the lowest-level retry helper. Generally, you'll use the
-    higher-level retry helper :class:`Retry`.
-
-    Args:
-        target(Callable): The function to call and retry. This must be a
-            nullary function - apply arguments with `functools.partial`.
-        predicate (Callable[Exception]): A callable used to determine if an
-            exception raised by the target should be considered retryable.
-            It should return True to retry or False otherwise.
-        sleep_generator (Iterable[float]): An infinite iterator that determines
-            how long to sleep between retries.
-        deadline (float): How long to keep retrying the target. The last sleep
-            period is shortened as necessary, so that the last retry runs at
-            ``deadline`` (and not considerably beyond it).
-        on_error (Callable[Exception]): A function to call while processing a
-            retryable exception.  Any error raised by this function will *not*
-            be caught.
-
-    Returns:
-        Any: the return value of the target function.
-
-    Raises:
-        google.api_core.RetryError: If the deadline is exceeded while retrying.
-        ValueError: If the sleep generator stops yielding values.
-        Exception: If the target raises a method that isn't retryable.
-    """
-    deadline_dt = (
-        (datetime_helpers.utcnow() + datetime.timedelta(seconds=deadline))
-        if deadline
-        else None
-    )
-
-    last_exc = None
-
-    for sleep in sleep_generator:
-        try:
-            if not deadline_dt:
-                return await target()
-            else:
-                return await asyncio.wait_for(
-                    target(),
-                    timeout=(deadline_dt - datetime_helpers.utcnow()).total_seconds(),
-                )
-        # pylint: disable=broad-except
-        # This function explicitly must deal with broad exceptions.
-        except Exception as exc:
-            if not predicate(exc) and not isinstance(exc, asyncio.TimeoutError):
-                raise
-            last_exc = exc
-            if on_error is not None:
-                on_error(exc)
-
-        now = datetime_helpers.utcnow()
-
-        if deadline_dt:
-            if deadline_dt <= now:
-                # Chains the raising RetryError with the root cause error,
-                # which helps observability and debugability.
-                raise exceptions.RetryError(
-                    "Deadline of {:.1f}s exceeded while calling {}".format(
-                        deadline, target
-                    ),
-                    last_exc,
-                ) from last_exc
-            else:
-                time_to_deadline = (deadline_dt - now).total_seconds()
-                sleep = min(time_to_deadline, sleep)
-
-        _LOGGER.debug(
-            "Retrying due to {}, sleeping {:.1f}s ...".format(last_exc, sleep)
-        )
-        await asyncio.sleep(sleep)
-
-    raise ValueError("Sleep generator stopped yielding sleep values.")
-
-
-class AsyncRetry:
-    """Exponential retry decorator for async functions.
-
-    This class is a decorator used to add exponential back-off retry behavior
-    to an RPC call.
-
-    Although the default behavior is to retry transient API errors, a
-    different predicate can be provided to retry other exceptions.
-
-    Args:
-        predicate (Callable[Exception]): A callable that should return ``True``
-            if the given exception is retryable.
-        initial (float): The minimum a,out of time to delay in seconds. This
-            must be greater than 0.
-        maximum (float): The maximum amout of time to delay in seconds.
-        multiplier (float): The multiplier applied to the delay.
-        deadline (float): How long to keep retrying in seconds. The last sleep
-            period is shortened as necessary, so that the last retry runs at
-            ``deadline`` (and not considerably beyond it).
-        on_error (Callable[Exception]): A function to call while processing
-            a retryable exception. Any error raised by this function will
-            *not* be caught.
-    """
-
-    def __init__(
-        self,
-        predicate=if_transient_error,
-        initial=_DEFAULT_INITIAL_DELAY,
-        maximum=_DEFAULT_MAXIMUM_DELAY,
-        multiplier=_DEFAULT_DELAY_MULTIPLIER,
-        deadline=_DEFAULT_DEADLINE,
-        on_error=None,
-    ):
-        self._predicate = predicate
-        self._initial = initial
-        self._multiplier = multiplier
-        self._maximum = maximum
-        self._deadline = deadline
-        self._on_error = on_error
-
-    def __call__(self, func, on_error=None):
-        """Wrap a callable with retry behavior.
-
-        Args:
-            func (Callable): The callable to add retry behavior to.
-            on_error (Callable[Exception]): A function to call while processing
-                a retryable exception. Any error raised by this function will
-                *not* be caught.
-
-        Returns:
-            Callable: A callable that will invoke ``func`` with retry
-                behavior.
-        """
-        if self._on_error is not None:
-            on_error = self._on_error
-
-        @functools.wraps(func)
-        async def retry_wrapped_func(*args, **kwargs):
-            """A wrapper that calls target function with retry."""
-            target = functools.partial(func, *args, **kwargs)
-            sleep_generator = exponential_sleep_generator(
-                self._initial, self._maximum, multiplier=self._multiplier
-            )
-            return await retry_target(
-                target,
-                self._predicate,
-                sleep_generator,
-                self._deadline,
-                on_error=on_error,
-            )
-
-        return retry_wrapped_func
-
-    def _replace(
-        self,
-        predicate=None,
-        initial=None,
-        maximum=None,
-        multiplier=None,
-        deadline=None,
-        on_error=None,
-    ):
-        return AsyncRetry(
-            predicate=predicate or self._predicate,
-            initial=initial or self._initial,
-            maximum=maximum or self._maximum,
-            multiplier=multiplier or self._multiplier,
-            deadline=deadline or self._deadline,
-            on_error=on_error or self._on_error,
-        )
-
-    def with_deadline(self, deadline):
-        """Return a copy of this retry with the given deadline.
-
-        Args:
-            deadline (float): How long to keep retrying.
-
-        Returns:
-            AsyncRetry: A new retry instance with the given deadline.
-        """
-        return self._replace(deadline=deadline)
-
-    def with_predicate(self, predicate):
-        """Return a copy of this retry with the given predicate.
-
-        Args:
-            predicate (Callable[Exception]): A callable that should return
-                ``True`` if the given exception is retryable.
-
-        Returns:
-            AsyncRetry: A new retry instance with the given predicate.
-        """
-        return self._replace(predicate=predicate)
-
-    def with_delay(self, initial=None, maximum=None, multiplier=None):
-        """Return a copy of this retry with the given delay options.
-
-        Args:
-            initial (float): The minimum amout of time to delay. This must
-                be greater than 0.
-            maximum (float): The maximum amout of time to delay.
-            multiplier (float): The multiplier applied to the delay.
-
-        Returns:
-            AsyncRetry: A new retry instance with the given predicate.
-        """
-        return self._replace(initial=initial, maximum=maximum, multiplier=multiplier)
-
-    def __str__(self):
-        return (
-            "<AsyncRetry predicate={}, initial={:.1f}, maximum={:.1f}, "
-            "multiplier={:.1f}, deadline={:.1f}, on_error={}>".format(
-                self._predicate,
-                self._initial,
-                self._maximum,
-                self._multiplier,
-                self._deadline,
-                self._on_error,
-            )
-        )
+from google.api_core.retry import if_transient_error  # noqa: F401
+from google.api_core.retry.retry_unary_async import AsyncRetry
+from google.api_core.retry.retry_unary_async import retry_target
+
+__all__ = (
+    "AsyncRetry",
+    "datetime_helpers",
+    "exceptions",
+    "exponential_sleep_generator",
+    "if_exception_type",
+    "if_transient_error",
+    "retry_target",
+)
diff --git a/google/api_core/timeout.py b/google/api_core/timeout.py
index 73232180..55b195e9 100644
--- a/google/api_core/timeout.py
+++ b/google/api_core/timeout.py
@@ -14,8 +14,9 @@
 
 """Decorators for applying timeout arguments to functions.
 
-These decorators are used to wrap API methods to apply either a constant
-or exponential timeout argument.
+These decorators are used to wrap API methods to apply either a
+Deadline-dependent (recommended), constant (DEPRECATED) or exponential
+(DEPRECATED) timeout argument.
 
 For example, imagine an API method that can take a while to return results,
 such as one that might block until a resource is ready:
@@ -66,9 +67,79 @@ def is_thing_ready(timeout=None):
 _DEFAULT_DEADLINE = None
 
 
+class TimeToDeadlineTimeout(object):
+    """A decorator that decreases timeout set for an RPC based on how much time
+    has left till its deadline. The deadline is calculated as
+    ``now + initial_timeout`` when this decorator is first called for an rpc.
+
+    In other words this decorator implements deadline semantics in terms of a
+    sequence of decreasing timeouts t0 > t1 > t2 ... tn >= 0.
+
+    Args:
+        timeout (Optional[float]): the timeout (in seconds) to applied to the
+            wrapped function. If `None`, the target function is expected to
+            never timeout.
+    """
+
+    def __init__(self, timeout=None, clock=datetime_helpers.utcnow):
+        self._timeout = timeout
+        self._clock = clock
+
+    def __call__(self, func):
+        """Apply the timeout decorator.
+
+        Args:
+            func (Callable): The function to apply the timeout argument to.
+                This function must accept a timeout keyword argument.
+
+        Returns:
+            Callable: The wrapped function.
+        """
+
+        first_attempt_timestamp = self._clock().timestamp()
+
+        @functools.wraps(func)
+        def func_with_timeout(*args, **kwargs):
+            """Wrapped function that adds timeout."""
+
+            if self._timeout is not None:
+                # All calculations are in seconds
+                now_timestamp = self._clock().timestamp()
+
+                # To avoid usage of nonlocal but still have round timeout
+                # numbers for first attempt (in most cases the only attempt made
+                # for an RPC.
+                if now_timestamp - first_attempt_timestamp < 0.001:
+                    now_timestamp = first_attempt_timestamp
+
+                time_since_first_attempt = now_timestamp - first_attempt_timestamp
+                remaining_timeout = self._timeout - time_since_first_attempt
+
+                # Although the `deadline` parameter in `google.api_core.retry.Retry`
+                # is deprecated, and should be treated the same as the `timeout`,
+                # it is still possible for the `deadline` argument in
+                # `google.api_core.retry.Retry` to be larger than the `timeout`.
+                # See https://github.com/googleapis/python-api-core/issues/654
+                # Only positive non-zero timeouts are supported.
+                # Revert back to the initial timeout for negative or 0 timeout values.
+                if remaining_timeout < 1:
+                    remaining_timeout = self._timeout
+
+                kwargs["timeout"] = remaining_timeout
+
+            return func(*args, **kwargs)
+
+        return func_with_timeout
+
+    def __str__(self):
+        return "<TimeToDeadlineTimeout timeout={:.1f}>".format(self._timeout)
+
+
 class ConstantTimeout(object):
     """A decorator that adds a constant timeout argument.
 
+    DEPRECATED: use ``TimeToDeadlineTimeout`` instead.
+
     This is effectively equivalent to
     ``functools.partial(func, timeout=timeout)``.
 
@@ -140,6 +211,9 @@ def _exponential_timeout_generator(initial, maximum, multiplier, deadline):
 class ExponentialTimeout(object):
     """A decorator that adds an exponentially increasing timeout argument.
 
+    DEPRECATED: the concept of incrementing timeout exponentially has been
+    deprecated. Use ``TimeToDeadlineTimeout`` instead.
+
     This is useful if a function is called multiple times. Each time the
     function is called this decorator will calculate a new timeout parameter
     based on the the number of times the function has been called.
@@ -156,9 +230,9 @@ class ExponentialTimeout(object):
         deadline (Optional[float]): The overall deadline across all
             invocations. This is used to prevent a very large calculated
             timeout from pushing the overall execution time over the deadline.
-            This is especially useful in conjuction with
+            This is especially useful in conjunction with
             :mod:`google.api_core.retry`. If ``None``, the timeouts will not
-            be adjusted to accomodate an overall deadline.
+            be adjusted to accommodate an overall deadline.
     """
 
     def __init__(
@@ -174,7 +248,7 @@ def __init__(
         self._deadline = deadline
 
     def with_deadline(self, deadline):
-        """Return a copy of this teimout with the given deadline.
+        """Return a copy of this timeout with the given deadline.
 
         Args:
             deadline (float): The overall deadline across all invocations.
diff --git a/google/api_core/universe.py b/google/api_core/universe.py
new file mode 100644
index 00000000..35669642
--- /dev/null
+++ b/google/api_core/universe.py
@@ -0,0 +1,82 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helpers for universe domain."""
+
+from typing import Any, Optional
+
+DEFAULT_UNIVERSE = "googleapis.com"
+
+
+class EmptyUniverseError(ValueError):
+    def __init__(self):
+        message = "Universe Domain cannot be an empty string."
+        super().__init__(message)
+
+
+class UniverseMismatchError(ValueError):
+    def __init__(self, client_universe, credentials_universe):
+        message = (
+            f"The configured universe domain ({client_universe}) does not match the universe domain "
+            f"found in the credentials ({credentials_universe}). "
+            "If you haven't configured the universe domain explicitly, "
+            f"`{DEFAULT_UNIVERSE}` is the default."
+        )
+        super().__init__(message)
+
+
+def determine_domain(
+    client_universe_domain: Optional[str], universe_domain_env: Optional[str]
+) -> str:
+    """Return the universe domain used by the client.
+
+    Args:
+        client_universe_domain (Optional[str]): The universe domain configured via the client options.
+        universe_domain_env (Optional[str]): The universe domain configured via the
+        "GOOGLE_CLOUD_UNIVERSE_DOMAIN" environment variable.
+
+    Returns:
+        str: The universe domain to be used by the client.
+
+    Raises:
+        ValueError: If the universe domain is an empty string.
+    """
+    universe_domain = DEFAULT_UNIVERSE
+    if client_universe_domain is not None:
+        universe_domain = client_universe_domain
+    elif universe_domain_env is not None:
+        universe_domain = universe_domain_env
+    if len(universe_domain.strip()) == 0:
+        raise EmptyUniverseError
+    return universe_domain
+
+
+def compare_domains(client_universe: str, credentials: Any) -> bool:
+    """Returns True iff the universe domains used by the client and credentials match.
+
+    Args:
+        client_universe (str): The universe domain configured via the client options.
+        credentials Any: The credentials being used in the client.
+
+    Returns:
+        bool: True iff client_universe matches the universe in credentials.
+
+    Raises:
+        ValueError: when client_universe does not match the universe in credentials.
+    """
+    credentials_universe = getattr(credentials, "universe_domain", DEFAULT_UNIVERSE)
+
+    if client_universe != credentials_universe:
+        raise UniverseMismatchError(client_universe, credentials_universe)
+    return True
diff --git a/google/api_core/version.py b/google/api_core/version.py
index 5fa77444..04ffe6a5 100644
--- a/google/api_core/version.py
+++ b/google/api_core/version.py
@@ -12,4 +12,4 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-__version__ = "2.0.0b1"
+__version__ = "2.24.2"
diff --git a/google/api_core/version_header.py b/google/api_core/version_header.py
new file mode 100644
index 00000000..cf1972ac
--- /dev/null
+++ b/google/api_core/version_header.py
@@ -0,0 +1,29 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+API_VERSION_METADATA_KEY = "x-goog-api-version"
+
+
+def to_api_version_header(version_identifier):
+    """Returns data for the API Version header for the given `version_identifier`.
+
+    Args:
+        version_identifier (str): The version identifier to be used in the
+            tuple returned.
+
+    Returns:
+        Tuple(str, str): A tuple containing the API Version metadata key and
+            value.
+    """
+    return (API_VERSION_METADATA_KEY, version_identifier)
diff --git a/noxfile.py b/noxfile.py
index 84470f5a..ac21330e 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -15,31 +15,42 @@
 from __future__ import absolute_import
 import os
 import pathlib
+import re
 import shutil
+import unittest
 
 # https://github.com/google/importlab/issues/25
 import nox  # pytype: disable=import-error
 
 
-BLACK_VERSION = "black==19.10b0"
+BLACK_VERSION = "black==22.3.0"
 BLACK_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
 # Black and flake8 clash on the syntax for ignoring flake8's F401 in this file.
 BLACK_EXCLUDES = ["--exclude", "^/google/api_core/operations_v1/__init__.py"]
 
-DEFAULT_PYTHON_VERSION = "3.7"
-CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
-
-_MINIMAL_ASYNCIO_SUPPORT_PYTHON_VERSION = [3, 6]
+PYTHON_VERSIONS = ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
 
+DEFAULT_PYTHON_VERSION = "3.10"
+CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
 
-def _greater_or_equal_than_36(version_string):
-    tokens = version_string.split(".")
-    for i, token in enumerate(tokens):
-        try:
-            tokens[i] = int(token)
-        except ValueError:
-            pass
-    return tokens >= [3, 6]
+# 'docfx' is excluded since it only needs to run in 'docs-presubmit'
+nox.options.sessions = [
+    "unit",
+    "unit_grpc_gcp",
+    "unit_wo_grpc",
+    "unit_w_prerelease_deps",
+    "unit_w_async_rest_extra",
+    "cover",
+    "pytype",
+    "mypy",
+    "lint",
+    "lint_setup_py",
+    "blacken",
+    "docs",
+]
+
+# Error if a python version is missing
+nox.options.error_on_missing_interpreters = True
 
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
@@ -49,10 +60,13 @@ def lint(session):
     Returns a failure if the linters find linting errors or sufficiently
     serious code quality issues.
     """
-    session.install("flake8", "flake8-import-order", BLACK_VERSION)
+    session.install("flake8", BLACK_VERSION)
     session.install(".")
     session.run(
-        "black", "--check", *BLACK_EXCLUDES, *BLACK_PATHS,
+        "black",
+        "--check",
+        *BLACK_EXCLUDES,
+        *BLACK_PATHS,
     )
     session.run("flake8", "google", "tests")
 
@@ -67,7 +81,37 @@ def blacken(session):
     session.run("black", *BLACK_EXCLUDES, *BLACK_PATHS)
 
 
-def default(session):
+def install_prerelease_dependencies(session, constraints_path):
+    with open(constraints_path, encoding="utf-8") as constraints_file:
+        constraints_text = constraints_file.read()
+        # Ignore leading whitespace and comment lines.
+        constraints_deps = [
+            match.group(1)
+            for match in re.finditer(
+                r"^\s*(\S+)(?===\S+)", constraints_text, flags=re.MULTILINE
+            )
+        ]
+        session.install(*constraints_deps)
+        prerel_deps = [
+            "google-auth",
+            "googleapis-common-protos",
+            "grpcio",
+            "grpcio-status",
+            "proto-plus",
+            "protobuf",
+        ]
+
+        for dep in prerel_deps:
+            session.install("--pre", "--no-deps", "--upgrade", dep)
+
+        # Remaining dependencies
+        other_deps = [
+            "requests",
+        ]
+        session.install(*other_deps)
+
+
+def default(session, install_grpc=True, prerelease=False, install_async_rest=False):
     """Default unit test session.
 
     This is intended to be run **without** an interpreter set, so
@@ -75,61 +119,144 @@ def default(session):
     Python corresponding to the ``nox`` binary the ``PATH`` can
     run the tests.
     """
-    constraints_path = str(
-        CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
+    if prerelease and not install_grpc:
+        unittest.skip("The pre-release session cannot be run without grpc")
+
+    session.install(
+        "dataclasses",
+        "mock; python_version=='3.7'",
+        "pytest",
+        "pytest-cov",
+        "pytest-xdist",
     )
 
-    # Install all test dependencies, then install this package in-place.
-    session.install("mock", "pytest", "pytest-cov")
-    session.install("-e", ".[grpc]", "-c", constraints_path)
+    install_extras = []
+    if install_grpc:
+        # Note: The extra is called `grpc` and not `grpcio`.
+        install_extras.append("grpc")
+
+    constraints_dir = str(CURRENT_DIRECTORY / "testing")
+    if install_async_rest:
+        install_extras.append("async_rest")
+        constraints_type = "async-rest-"
+    else:
+        constraints_type = ""
+
+    lib_with_extras = f".[{','.join(install_extras)}]" if len(install_extras) else "."
+    if prerelease:
+        install_prerelease_dependencies(
+            session,
+            f"{constraints_dir}/constraints-{constraints_type}{PYTHON_VERSIONS[0]}.txt",
+        )
+        # This *must* be the last install command to get the package from source.
+        session.install("-e", lib_with_extras, "--no-deps")
+    else:
+        constraints_file = (
+            f"{constraints_dir}/constraints-{constraints_type}{session.python}.txt"
+        )
+        # fall back to standard constraints file
+        if not pathlib.Path(constraints_file).exists():
+            constraints_file = f"{constraints_dir}/constraints-{session.python}.txt"
+
+        session.install(
+            "-e",
+            lib_with_extras,
+            "-c",
+            constraints_file,
+        )
+
+    # Print out package versions of dependencies
+    session.run(
+        "python", "-c", "import google.protobuf; print(google.protobuf.__version__)"
+    )
+    # Support for proto.version was added in v1.23.0
+    # https://github.com/googleapis/proto-plus-python/releases/tag/v1.23.0
+    session.run(
+        "python",
+        "-c",
+        """import proto; hasattr(proto, "version") and print(proto.version.__version__)""",
+    )
+    if install_grpc:
+        session.run("python", "-c", "import grpc; print(grpc.__version__)")
+    session.run("python", "-c", "import google.auth; print(google.auth.__version__)")
 
     pytest_args = [
         "python",
         "-m",
-        "py.test",
-        "--quiet",
-        "--cov=google.api_core",
-        "--cov=tests.unit",
-        "--cov-append",
-        "--cov-config=.coveragerc",
-        "--cov-report=",
-        "--cov-fail-under=0",
-        os.path.join("tests", "unit"),
+        "pytest",
+        *(
+            # Helpful for running a single test or testfile.
+            session.posargs
+            or [
+                "--quiet",
+                "--cov=google.api_core",
+                "--cov=tests.unit",
+                "--cov-append",
+                "--cov-config=.coveragerc",
+                "--cov-report=",
+                "--cov-fail-under=0",
+                # Running individual tests with parallelism enabled is usually not helpful.
+                "-n=auto",
+                os.path.join("tests", "unit"),
+            ]
+        ),
     ]
-    pytest_args.extend(session.posargs)
 
-    # Inject AsyncIO content and proto-plus, if version >= 3.6.
-    # proto-plus is needed for a field mask test in test_protobuf_helpers.py
-    if _greater_or_equal_than_36(session.python):
-        session.install("asyncmock", "pytest-asyncio", "proto-plus")
+    session.install("asyncmock", "pytest-asyncio")
 
+    # Having positional arguments means the user wants to run specific tests.
+    # Best not to add additional tests to that list.
+    if not session.posargs:
         pytest_args.append("--cov=tests.asyncio")
         pytest_args.append(os.path.join("tests", "asyncio"))
-        session.run(*pytest_args)
-    else:
-        # Run py.test against the unit tests.
-        session.run(*pytest_args)
 
+    session.run(*pytest_args)
 
-@nox.session(python=["3.6", "3.7", "3.8", "3.9"])
+
+@nox.session(python=PYTHON_VERSIONS)
 def unit(session):
     """Run the unit test suite."""
     default(session)
 
 
-@nox.session(python=["3.6", "3.7", "3.8", "3.9"])
+@nox.session(python=PYTHON_VERSIONS)
+def unit_w_prerelease_deps(session):
+    """Run the unit test suite."""
+    default(session, prerelease=True)
+
+
+@nox.session(python=PYTHON_VERSIONS)
 def unit_grpc_gcp(session):
-    """Run the unit test suite with grpcio-gcp installed."""
+    """
+    Run the unit test suite with grpcio-gcp installed.
+    `grpcio-gcp` doesn't support protobuf 4+.
+    Remove extra `grpcgcp` when protobuf 3.x is dropped.
+    https://github.com/googleapis/python-api-core/issues/594
+    """
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
     # Install grpcio-gcp
     session.install("-e", ".[grpcgcp]", "-c", constraints_path)
+    # Install protobuf < 4.0.0
+    session.install("protobuf<4.0.0")
 
     default(session)
 
 
-@nox.session(python="3.6")
+@nox.session(python=PYTHON_VERSIONS)
+def unit_wo_grpc(session):
+    """Run the unit test suite w/o grpcio installed"""
+    default(session, install_grpc=False)
+
+
+@nox.session(python=PYTHON_VERSIONS)
+def unit_w_async_rest_extra(session):
+    """Run the unit test suite with the `async_rest` extra"""
+    default(session, install_async_rest=True)
+
+
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def lint_setup_py(session):
     """Verify that setup.py is valid (including RST check)."""
 
@@ -137,15 +264,28 @@ def lint_setup_py(session):
     session.run("python", "setup.py", "check", "--restructuredtext", "--strict")
 
 
-# No 3.7 because pytype supports up to 3.6 only.
-@nox.session(python="3.6")
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def pytype(session):
     """Run type-checking."""
-    session.install(".[grpc, grpcgcp]", "pytype >= 2019.3.21")
+    session.install(".[grpc]", "pytype")
     session.run("pytype")
 
 
-@nox.session(python="3.6")
+@nox.session(python=DEFAULT_PYTHON_VERSION)
+def mypy(session):
+    """Run type-checking."""
+    session.install(".[grpc,async_rest]", "mypy")
+    session.install(
+        "types-setuptools",
+        "types-requests",
+        "types-protobuf",
+        "types-dataclasses",
+        "types-mock; python_version=='3.7'",
+    )
+    session.run("mypy", "google", "tests")
+
+
+@nox.session(python=DEFAULT_PYTHON_VERSION)
 def cover(session):
     """Run the final coverage report.
 
@@ -157,12 +297,25 @@ def cover(session):
     session.run("coverage", "erase")
 
 
-@nox.session(python="3.8")
+@nox.session(python="3.10")
 def docs(session):
     """Build the docs for this library."""
 
-    session.install("-e", ".[grpc, grpcgcp]")
-    session.install("sphinx==4.0.1", "alabaster", "recommonmark")
+    session.install("-e", ".[grpc]")
+    session.install(
+        # We need to pin to specific versions of the `sphinxcontrib-*` packages
+        # which still support sphinx 4.x.
+        # See https://github.com/googleapis/sphinx-docfx-yaml/issues/344
+        # and https://github.com/googleapis/sphinx-docfx-yaml/issues/345.
+        "sphinxcontrib-applehelp==1.0.4",
+        "sphinxcontrib-devhelp==1.0.2",
+        "sphinxcontrib-htmlhelp==2.0.1",
+        "sphinxcontrib-qthelp==1.0.3",
+        "sphinxcontrib-serializinghtml==1.1.5",
+        "sphinx==4.5.0",
+        "alabaster",
+        "recommonmark",
+    )
 
     shutil.rmtree(os.path.join("docs", "_build"), ignore_errors=True)
     session.run(
@@ -179,13 +332,24 @@ def docs(session):
     )
 
 
-@nox.session(python="3.8")
+@nox.session(python="3.10")
 def docfx(session):
     """Build the docfx yaml files for this library."""
 
     session.install("-e", ".")
     session.install(
-        "sphinx==4.0.1", "alabaster", "recommonmark", "gcp-sphinx-docfx-yaml"
+        # We need to pin to specific versions of the `sphinxcontrib-*` packages
+        # which still support sphinx 4.x.
+        # See https://github.com/googleapis/sphinx-docfx-yaml/issues/344
+        # and https://github.com/googleapis/sphinx-docfx-yaml/issues/345.
+        "sphinxcontrib-applehelp==1.0.4",
+        "sphinxcontrib-devhelp==1.0.2",
+        "sphinxcontrib-htmlhelp==2.0.1",
+        "sphinxcontrib-qthelp==1.0.3",
+        "sphinxcontrib-serializinghtml==1.1.5",
+        "gcp-sphinx-docfx-yaml",
+        "alabaster",
+        "recommonmark",
     )
 
     shutil.rmtree(os.path.join("docs", "_build"), ignore_errors=True)
diff --git a/owlbot.py b/owlbot.py
index 451f7c48..58bc7517 100644
--- a/owlbot.py
+++ b/owlbot.py
@@ -16,6 +16,7 @@
 
 import synthtool as s
 from synthtool import gcp
+from synthtool.languages import python
 
 common = gcp.CommonTemplates()
 
@@ -25,23 +26,15 @@
 excludes = [
     "noxfile.py",  # pytype
     "setup.cfg",  # pytype
-    ".flake8",  # flake8-import-order, layout
     ".coveragerc",  # layout
     "CONTRIBUTING.rst",  # no systests
+    ".github/workflows/unittest.yml",  # exclude unittest gh action
+    ".github/workflows/lint.yml",  # exclude lint gh action
+    "README.rst",
 ]
 templated_files = common.py_library(microgenerator=True, cov_level=100)
 s.move(templated_files, excludes=excludes)
 
-# Add pytype support
-s.replace(
-    ".gitignore",
-    """\
-.pytest_cache
-""",
-    """\
-.pytest_cache
-.pytype
-""",
-)
+python.configure_previous_major_version_branches()
 
 s.shell.run(["nox", "-s", "blacken"], hide_output=False)
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 00000000..da404ab3
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,107 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+[build-system]
+requires = ["setuptools"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "google-api-core"
+authors = [{ name = "Google LLC", email = "googleapis-packages@google.com" }]
+license = { text = "Apache 2.0" }
+requires-python = ">=3.7"
+readme = "README.rst"
+description = "Google API client core library"
+classifiers = [
+  # Should be one of:
+  # "Development Status :: 3 - Alpha"
+  # "Development Status :: 4 - Beta"
+  # "Development Status :: 5 - Production/Stable"
+  "Development Status :: 5 - Production/Stable",
+  "Intended Audience :: Developers",
+  "License :: OSI Approved :: Apache Software License",
+  "Programming Language :: Python",
+  "Programming Language :: Python :: 3",
+  "Programming Language :: Python :: 3.7",
+  "Programming Language :: Python :: 3.8",
+  "Programming Language :: Python :: 3.9",
+  "Programming Language :: Python :: 3.10",
+  "Programming Language :: Python :: 3.11",
+  "Programming Language :: Python :: 3.12",
+  "Programming Language :: Python :: 3.13",
+  "Operating System :: OS Independent",
+  "Topic :: Internet",
+]
+dependencies = [
+  "googleapis-common-protos >= 1.56.2, < 2.0.0",
+  "protobuf >= 3.19.5, < 7.0.0, != 3.20.0, != 3.20.1, != 4.21.0, != 4.21.1, != 4.21.2, != 4.21.3, != 4.21.4, != 4.21.5",
+  "proto-plus >= 1.22.3, < 2.0.0",
+  "proto-plus >= 1.25.0, < 2.0.0; python_version >= '3.13'",
+  "google-auth >= 2.14.1, < 3.0.0",
+  "requests >= 2.18.0, < 3.0.0",
+]
+dynamic = ["version"]
+
+[project.urls]
+Documentation = "https://googleapis.dev/python/google-api-core/latest/"
+Repository = "https://github.com/googleapis/python-api-core"
+
+[project.optional-dependencies]
+async_rest = ["google-auth[aiohttp] >= 2.35.0, < 3.0.0"]
+grpc = [
+  "grpcio >= 1.33.2, < 2.0.0",
+  "grpcio >= 1.49.1, < 2.0.0; python_version >= '3.11'",
+  "grpcio-status >= 1.33.2, < 2.0.0",
+  "grpcio-status >= 1.49.1, < 2.0.0; python_version >= '3.11'",
+]
+grpcgcp = ["grpcio-gcp >= 0.2.2, < 1.0.0"]
+grpcio-gcp = ["grpcio-gcp >= 0.2.2, < 1.0.0"]
+
+[tool.setuptools.dynamic]
+version = { attr = "google.api_core.version.__version__" }
+
+[tool.setuptools.packages.find]
+# Only include packages under the 'google' namespace. Do not include tests,
+# benchmarks, etc.
+include = ["google*"]
+
+[tool.mypy]
+python_version = "3.7"
+namespace_packages = true
+ignore_missing_imports = true
+
+[tool.pytest]
+filterwarnings = [
+  # treat all warnings as errors
+  "error",
+  # Remove once https://github.com/pytest-dev/pytest-cov/issues/621 is fixed
+  "ignore:.*The --rsyncdir command line argument and rsyncdirs config variable are deprecated:DeprecationWarning",
+  # Remove once https://github.com/protocolbuffers/protobuf/issues/12186 is fixed
+  "ignore:.*custom tp_new.*in Python 3.14:DeprecationWarning",
+  # Remove once support for python 3.7 is dropped
+  # This warning only appears when using python 3.7
+  "ignore:.*Using or importing the ABCs from.*collections:DeprecationWarning",
+  # Remove once support for grpcio-gcp is deprecated
+  # See https://github.com/googleapis/python-api-core/blob/42e8b6e6f426cab749b34906529e8aaf3f133d75/google/api_core/grpc_helpers.py#L39-L45
+  "ignore:.*Support for grpcio-gcp is deprecated:DeprecationWarning",
+  "ignore: The `compression` argument is ignored for grpc_gcp.secure_channel creation:DeprecationWarning",
+  "ignore:The `attempt_direct_path` argument is ignored for grpc_gcp.secure_channel creation:DeprecationWarning",
+  # Remove once the minimum supported version of googleapis-common-protos is 1.62.0
+  "ignore:.*pkg_resources.declare_namespace:DeprecationWarning",
+  "ignore:.*pkg_resources is deprecated as an API:DeprecationWarning",
+  # Remove once https://github.com/grpc/grpc/issues/35086 is fixed (and version newer than 1.60.0 is published)
+  "ignore:There is no current event loop:DeprecationWarning",
+  # Remove after support for Python 3.7 is dropped
+  "ignore:After January 1, 2024, new releases of this library will drop support for Python 3.7:DeprecationWarning",
+]
diff --git a/renovate.json b/renovate.json
index c0489556..c7875c46 100644
--- a/renovate.json
+++ b/renovate.json
@@ -1,8 +1,11 @@
 {
   "extends": [
-    "config:base",  ":preserveSemverRanges"
+    "config:base",
+    "group:all",
+    ":preserveSemverRanges",
+    ":disableDependencyDashboard"
   ],
-  "ignorePaths": [".pre-commit-config.yaml"],
+  "ignorePaths": [".pre-commit-config.yaml", ".kokoro/requirements.txt", "setup.py", ".github/workflows/unittest.yml"],
   "pip_requirements": {
     "fileMatch": ["requirements-test.txt", "samples/[\\S/]*constraints.txt", "samples/[\\S/]*constraints-test.txt"]
   }
diff --git a/scripts/decrypt-secrets.sh b/scripts/decrypt-secrets.sh
index 21f6d2a2..120b0ddc 100755
--- a/scripts/decrypt-secrets.sh
+++ b/scripts/decrypt-secrets.sh
@@ -1,6 +1,6 @@
 #!/bin/bash
 
-# Copyright 2015 Google Inc. All rights reserved.
+# Copyright 2024 Google LLC All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
diff --git a/scripts/readme-gen/readme_gen.py b/scripts/readme-gen/readme_gen.py
index d309d6e9..8f5e248a 100644
--- a/scripts/readme-gen/readme_gen.py
+++ b/scripts/readme-gen/readme_gen.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python
 
-# Copyright 2016 Google Inc
+# Copyright 2024 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -28,19 +28,22 @@
 jinja_env = jinja2.Environment(
     trim_blocks=True,
     loader=jinja2.FileSystemLoader(
-        os.path.abspath(os.path.join(os.path.dirname(__file__), 'templates'))))
+        os.path.abspath(os.path.join(os.path.dirname(__file__), "templates"))
+    ),
+    autoescape=True,
+)
 
-README_TMPL = jinja_env.get_template('README.tmpl.rst')
+README_TMPL = jinja_env.get_template("README.tmpl.rst")
 
 
 def get_help(file):
-    return subprocess.check_output(['python', file, '--help']).decode()
+    return subprocess.check_output(["python", file, "--help"]).decode()
 
 
 def main():
     parser = argparse.ArgumentParser()
-    parser.add_argument('source')
-    parser.add_argument('--destination', default='README.rst')
+    parser.add_argument("source")
+    parser.add_argument("--destination", default="README.rst")
 
     args = parser.parse_args()
 
@@ -48,9 +51,9 @@ def main():
     root = os.path.dirname(source)
     destination = os.path.join(root, args.destination)
 
-    jinja_env.globals['get_help'] = get_help
+    jinja_env.globals["get_help"] = get_help
 
-    with io.open(source, 'r') as f:
+    with io.open(source, "r") as f:
         config = yaml.load(f)
 
     # This allows get_help to execute in the right directory.
@@ -58,9 +61,9 @@ def main():
 
     output = README_TMPL.render(config)
 
-    with io.open(destination, 'w') as f:
+    with io.open(destination, "w") as f:
         f.write(output)
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     main()
diff --git a/scripts/readme-gen/templates/install_deps.tmpl.rst b/scripts/readme-gen/templates/install_deps.tmpl.rst
index a0406dba..6f069c6c 100644
--- a/scripts/readme-gen/templates/install_deps.tmpl.rst
+++ b/scripts/readme-gen/templates/install_deps.tmpl.rst
@@ -12,7 +12,7 @@ Install Dependencies
    .. _Python Development Environment Setup Guide:
        https://cloud.google.com/python/setup
 
-#. Create a virtualenv. Samples are compatible with Python 2.7 and 3.4+.
+#. Create a virtualenv. Samples are compatible with Python 3.7+.
 
     .. code-block:: bash
 
diff --git a/setup.cfg b/setup.cfg
index 0be0b3ff..f7b5a3bc 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,8 +1,5 @@
-[bdist_wheel]
-universal = 1
-
 [pytype]
-python_version = 3.6
+python_version = 3.7
 inputs =
     google/
 exclude =
diff --git a/setup.py b/setup.py
index d98c69c5..168877fa 100644
--- a/setup.py
+++ b/setup.py
@@ -12,91 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import io
-import os
-
 import setuptools
 
 
-# Package metadata.
-
-name = "google-api-core"
-description = "Google API client core library"
-
-# Should be one of:
-# 'Development Status :: 3 - Alpha'
-# 'Development Status :: 4 - Beta'
-# 'Development Status :: 5 - Production/Stable'
-release_status = "Development Status :: 5 - Production/Stable"
-dependencies = [
-    "googleapis-common-protos >= 1.6.0, < 2.0dev",
-    "protobuf >= 3.12.0",
-    "google-auth >= 1.25.0, < 3.0dev",
-    "requests >= 2.18.0, < 3.0.0dev",
-    "setuptools >= 40.3.0",
-    'futures >= 3.2.0; python_version < "3.2"',
-]
-extras = {
-    "grpc": "grpcio >= 1.29.0, < 2.0dev",
-    "grpcgcp": "grpcio-gcp >= 0.2.2",
-    "grpcio-gcp": "grpcio-gcp >= 0.2.2",
-}
-
-
-# Setup boilerplate below this line.
-
-package_root = os.path.abspath(os.path.dirname(__file__))
-
-
-version = {}
-with open(os.path.join(package_root, "google/api_core/version.py")) as fp:
-    exec(fp.read(), version)
-version = version["__version__"]
-
-readme_filename = os.path.join(package_root, "README.rst")
-with io.open(readme_filename, encoding="utf-8") as readme_file:
-    readme = readme_file.read()
-
-# Only include packages under the 'google' namespace. Do not include tests,
-# benchmarks, etc.
-packages = [
-    package for package in setuptools.find_packages() if package.startswith("google")
-]
-
-# Determine which namespaces are needed.
-namespaces = ["google"]
-if "google.cloud" in packages:
-    namespaces.append("google.cloud")
-
-
-setuptools.setup(
-    name=name,
-    version=version,
-    description=description,
-    long_description=readme,
-    author="Google LLC",
-    author_email="googleapis-packages@google.com",
-    license="Apache 2.0",
-    url="https://github.com/googleapis/python-api-core",
-    classifiers=[
-        release_status,
-        "Intended Audience :: Developers",
-        "License :: OSI Approved :: Apache Software License",
-        "Programming Language :: Python",
-        "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.6",
-        "Programming Language :: Python :: 3.7",
-        "Programming Language :: Python :: 3.8",
-        "Programming Language :: Python :: 3.9",
-        "Operating System :: OS Independent",
-        "Topic :: Internet",
-    ],
-    platforms="Posix; MacOS X; Windows",
-    packages=packages,
-    namespace_packages=namespaces,
-    install_requires=dependencies,
-    extras_require=extras,
-    python_requires=">=3.6",
-    include_package_data=True,
-    zip_safe=False,
-)
+setuptools.setup()
diff --git a/testing/constraints-3.12.txt b/testing/constraints-3.12.txt
new file mode 100644
index 00000000..e69de29b
diff --git a/testing/constraints-3.13.txt b/testing/constraints-3.13.txt
new file mode 100644
index 00000000..e69de29b
diff --git a/testing/constraints-3.14.txt b/testing/constraints-3.14.txt
new file mode 100644
index 00000000..e69de29b
diff --git a/testing/constraints-3.7.txt b/testing/constraints-3.7.txt
index e69de29b..4ce1c899 100644
--- a/testing/constraints-3.7.txt
+++ b/testing/constraints-3.7.txt
@@ -0,0 +1,15 @@
+# This constraints file is used to check that lower bounds
+# are correct in setup.py
+# List *all* library dependencies and extras in this file.
+# Pin the version to the lower bound.
+#
+# e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
+# Then this file should have foo==1.14.0
+googleapis-common-protos==1.56.2
+protobuf==3.19.5
+google-auth==2.14.1
+requests==2.18.0
+grpcio==1.33.2
+grpcio-status==1.33.2
+grpcio-gcp==0.2.2
+proto-plus==1.22.3
diff --git a/testing/constraints-3.8.txt b/testing/constraints-3.8.txt
index e69de29b..1b5bb58e 100644
--- a/testing/constraints-3.8.txt
+++ b/testing/constraints-3.8.txt
@@ -0,0 +1,2 @@
+googleapis-common-protos==1.56.3
+protobuf==4.21.6
\ No newline at end of file
diff --git a/testing/constraints-3.6.txt b/testing/constraints-async-rest-3.7.txt
similarity index 61%
rename from testing/constraints-3.6.txt
rename to testing/constraints-async-rest-3.7.txt
index 2544e8e5..7aedeb1c 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-async-rest-3.7.txt
@@ -5,12 +5,13 @@
 #
 # e.g., if setup.py has "foo >= 1.14.0, < 2.0.0dev",
 # Then this file should have foo==1.14.0
-googleapis-common-protos==1.6.0
-protobuf==3.12.0
-google-auth==1.25.0
-requests==2.18.0
-setuptools==40.3.0
-packaging==14.3
-grpcio==1.29.0
-grpcio-gcp==0.2.2
+googleapis-common-protos==1.56.2
+protobuf==3.19.5
+google-auth==2.35.0
+# from google-auth[aiohttp]
+aiohttp==3.6.2
+requests==2.20.0
+grpcio==1.33.2
+grpcio-status==1.33.2
 grpcio-gcp==0.2.2
+proto-plus==1.22.3
diff --git a/tests/asyncio/future/test_async_future.py b/tests/asyncio/future/test_async_future.py
index 1e9ae334..659f41cf 100644
--- a/tests/asyncio/future/test_async_future.py
+++ b/tests/asyncio/future/test_async_future.py
@@ -13,8 +13,8 @@
 # limitations under the License.
 
 import asyncio
+from unittest import mock
 
-import mock
 import pytest
 
 from google.api_core import exceptions
@@ -47,7 +47,6 @@ async def test_polling_future_constructor():
 @pytest.mark.asyncio
 async def test_set_result():
     future = AsyncFuture()
-    callback = mock.Mock()
 
     future.set_result(1)
 
diff --git a/tests/asyncio/gapic/test_config_async.py b/tests/asyncio/gapic/test_config_async.py
index 1f6ea9e2..dbb05d5e 100644
--- a/tests/asyncio/gapic/test_config_async.py
+++ b/tests/asyncio/gapic/test_config_async.py
@@ -12,6 +12,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+
+import pytest
+
+try:
+    import grpc  # noqa: F401
+except ImportError:
+    pytest.skip("No GRPC", allow_module_level=True)
+
 from google.api_core import exceptions
 from google.api_core.gapic_v1 import config_async
 
diff --git a/tests/asyncio/gapic/test_method_async.py b/tests/asyncio/gapic/test_method_async.py
index 2c6bbab9..73f67b8d 100644
--- a/tests/asyncio/gapic/test_method_async.py
+++ b/tests/asyncio/gapic/test_method_async.py
@@ -14,10 +14,18 @@
 
 import datetime
 
-from grpc.experimental import aio
-import mock
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock  # pragma: NO COVER  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    import mock  # type: ignore
 import pytest
 
+try:
+    from grpc import aio, Compression
+except ImportError:
+    pytest.skip("No GRPC", allow_module_level=True)
+
 from google.api_core import exceptions
 from google.api_core import gapic_v1
 from google.api_core import grpc_helpers_async
@@ -88,6 +96,35 @@ async def test_wrap_method_with_custom_client_info():
     assert client_info.to_grpc_metadata() in metadata
 
 
+@pytest.mark.asyncio
+async def test_wrap_method_with_no_compression():
+    fake_call = grpc_helpers_async.FakeUnaryUnaryCall()
+    method = mock.Mock(spec=aio.UnaryUnaryMultiCallable, return_value=fake_call)
+
+    wrapped_method = gapic_v1.method_async.wrap_method(method)
+
+    await wrapped_method(1, 2, meep="moop", compression=None)
+
+    method.assert_called_once_with(1, 2, meep="moop", metadata=mock.ANY)
+
+
+@pytest.mark.asyncio
+async def test_wrap_method_with_custom_compression():
+    compression = Compression.Gzip
+    fake_call = grpc_helpers_async.FakeUnaryUnaryCall()
+    method = mock.Mock(spec=aio.UnaryUnaryMultiCallable, return_value=fake_call)
+
+    wrapped_method = gapic_v1.method_async.wrap_method(
+        method, default_compression=compression
+    )
+
+    await wrapped_method(1, 2, meep="moop", compression=Compression.Deflate)
+
+    method.assert_called_once_with(
+        1, 2, meep="moop", metadata=mock.ANY, compression=Compression.Deflate
+    )
+
+
 @pytest.mark.asyncio
 async def test_invoke_wrapped_method_with_metadata():
     fake_call = grpc_helpers_async.FakeUnaryUnaryCall()
@@ -122,7 +159,7 @@ async def test_invoke_wrapped_method_with_metadata_as_none():
 
 @mock.patch("asyncio.sleep")
 @pytest.mark.asyncio
-async def test_wrap_method_with_default_retry_and_timeout(unused_sleep):
+async def test_wrap_method_with_default_retry_timeout_and_compression(unused_sleep):
     fake_call = grpc_helpers_async.FakeUnaryUnaryCall(42)
     method = mock.Mock(
         spec=aio.UnaryUnaryMultiCallable,
@@ -131,15 +168,18 @@ async def test_wrap_method_with_default_retry_and_timeout(unused_sleep):
 
     default_retry = retry_async.AsyncRetry()
     default_timeout = timeout.ConstantTimeout(60)
+    default_compression = Compression.Gzip
     wrapped_method = gapic_v1.method_async.wrap_method(
-        method, default_retry, default_timeout
+        method, default_retry, default_timeout, default_compression
     )
 
     result = await wrapped_method()
 
     assert result == 42
     assert method.call_count == 2
-    method.assert_called_with(timeout=60, metadata=mock.ANY)
+    method.assert_called_with(
+        timeout=60, compression=default_compression, metadata=mock.ANY
+    )
 
 
 @mock.patch("asyncio.sleep")
@@ -153,22 +193,27 @@ async def test_wrap_method_with_default_retry_and_timeout_using_sentinel(unused_
 
     default_retry = retry_async.AsyncRetry()
     default_timeout = timeout.ConstantTimeout(60)
+    default_compression = Compression.Gzip
     wrapped_method = gapic_v1.method_async.wrap_method(
-        method, default_retry, default_timeout
+        method, default_retry, default_timeout, default_compression
     )
 
     result = await wrapped_method(
-        retry=gapic_v1.method_async.DEFAULT, timeout=gapic_v1.method_async.DEFAULT,
+        retry=gapic_v1.method_async.DEFAULT,
+        timeout=gapic_v1.method_async.DEFAULT,
+        compression=gapic_v1.method_async.DEFAULT,
     )
 
     assert result == 42
     assert method.call_count == 2
-    method.assert_called_with(timeout=60, metadata=mock.ANY)
+    method.assert_called_with(
+        timeout=60, compression=Compression.Gzip, metadata=mock.ANY
+    )
 
 
 @mock.patch("asyncio.sleep")
 @pytest.mark.asyncio
-async def test_wrap_method_with_overriding_retry_and_timeout(unused_sleep):
+async def test_wrap_method_with_overriding_retry_timeout_and_compression(unused_sleep):
     fake_call = grpc_helpers_async.FakeUnaryUnaryCall(42)
     method = mock.Mock(
         spec=aio.UnaryUnaryMultiCallable,
@@ -177,8 +222,9 @@ async def test_wrap_method_with_overriding_retry_and_timeout(unused_sleep):
 
     default_retry = retry_async.AsyncRetry()
     default_timeout = timeout.ConstantTimeout(60)
+    default_compression = Compression.Gzip
     wrapped_method = gapic_v1.method_async.wrap_method(
-        method, default_retry, default_timeout
+        method, default_retry, default_timeout, default_compression
     )
 
     result = await wrapped_method(
@@ -186,45 +232,13 @@ async def test_wrap_method_with_overriding_retry_and_timeout(unused_sleep):
             retry_async.if_exception_type(exceptions.NotFound)
         ),
         timeout=timeout.ConstantTimeout(22),
+        compression=Compression.Deflate,
     )
 
     assert result == 42
     assert method.call_count == 2
-    method.assert_called_with(timeout=22, metadata=mock.ANY)
-
-
-@mock.patch("asyncio.sleep")
-@mock.patch(
-    "google.api_core.datetime_helpers.utcnow",
-    side_effect=_utcnow_monotonic(),
-    autospec=True,
-)
-@pytest.mark.asyncio
-async def test_wrap_method_with_overriding_retry_deadline(utcnow, unused_sleep):
-    fake_call = grpc_helpers_async.FakeUnaryUnaryCall(42)
-    method = mock.Mock(
-        spec=aio.UnaryUnaryMultiCallable,
-        side_effect=([exceptions.InternalServerError(None)] * 4) + [fake_call],
-    )
-
-    default_retry = retry_async.AsyncRetry()
-    default_timeout = timeout.ExponentialTimeout(deadline=60)
-    wrapped_method = gapic_v1.method_async.wrap_method(
-        method, default_retry, default_timeout
-    )
-
-    # Overriding only the retry's deadline should also override the timeout's
-    # deadline.
-    result = await wrapped_method(retry=default_retry.with_deadline(30))
-
-    assert result == 42
-    timeout_args = [call[1]["timeout"] for call in method.call_args_list]
-    assert timeout_args == [5.0, 10.0, 20.0, 26.0, 25.0]
-    assert utcnow.call_count == (
-        1
-        + 1  # Compute wait_for timeout in retry_async
-        + 5  # First to set the deadline.
-        + 5  # One for each min(timeout, maximum, (DEADLINE - NOW).seconds)
+    method.assert_called_with(
+        timeout=22, compression=Compression.Deflate, metadata=mock.ANY
     )
 
 
@@ -242,3 +256,14 @@ async def test_wrap_method_with_overriding_timeout_as_a_number():
 
     assert result == 42
     method.assert_called_once_with(timeout=22, metadata=mock.ANY)
+
+
+@pytest.mark.asyncio
+async def test_wrap_method_without_wrap_errors():
+    fake_call = mock.AsyncMock()
+
+    wrapped_method = gapic_v1.method_async.wrap_method(fake_call, kind="rest")
+    with mock.patch("google.api_core.grpc_helpers_async.wrap_errors") as method:
+        await wrapped_method()
+
+        method.assert_not_called()
diff --git a/tests/asyncio/operations_v1/test_operations_async_client.py b/tests/asyncio/operations_v1/test_operations_async_client.py
index 5473e8ae..e5b20dcd 100644
--- a/tests/asyncio/operations_v1/test_operations_async_client.py
+++ b/tests/asyncio/operations_v1/test_operations_async_client.py
@@ -12,11 +12,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from grpc.experimental import aio
-import mock
+from unittest import mock
+
 import pytest
 
-from google.api_core import grpc_helpers_async, operations_v1, page_iterator_async
+try:
+    from grpc import aio, Compression
+except ImportError:  # pragma: NO COVER
+    pytest.skip("No GRPC", allow_module_level=True)
+
+from google.api_core import grpc_helpers_async
+from google.api_core import operations_v1
+from google.api_core import page_iterator_async
 from google.longrunning import operations_pb2
 from google.protobuf import empty_pb2
 
@@ -36,10 +43,13 @@ async def test_get_operation():
     )
     client = operations_v1.OperationsAsyncClient(mocked_channel)
 
-    response = await client.get_operation("name", metadata=[("header", "foo")])
+    response = await client.get_operation(
+        "name", metadata=[("header", "foo")], compression=Compression.Gzip
+    )
     assert method.call_count == 1
     assert tuple(method.call_args_list[0])[0][0].name == "name"
     assert ("header", "foo") in tuple(method.call_args_list[0])[1]["metadata"]
+    assert tuple(method.call_args_list[0])[1]["compression"] == Compression.Gzip
     assert ("x-goog-request-params", "name=name") in tuple(method.call_args_list[0])[1][
         "metadata"
     ]
@@ -57,7 +67,9 @@ async def test_list_operations():
     mocked_channel, method, fake_call = _mock_grpc_objects(list_response)
     client = operations_v1.OperationsAsyncClient(mocked_channel)
 
-    pager = await client.list_operations("name", "filter", metadata=[("header", "foo")])
+    pager = await client.list_operations(
+        "name", "filter", metadata=[("header", "foo")], compression=Compression.Gzip
+    )
 
     assert isinstance(pager, page_iterator_async.AsyncIterator)
     responses = []
@@ -68,6 +80,7 @@ async def test_list_operations():
 
     assert method.call_count == 1
     assert ("header", "foo") in tuple(method.call_args_list[0])[1]["metadata"]
+    assert tuple(method.call_args_list[0])[1]["compression"] == Compression.Gzip
     assert ("x-goog-request-params", "name=name") in tuple(method.call_args_list[0])[1][
         "metadata"
     ]
@@ -82,11 +95,14 @@ async def test_delete_operation():
     mocked_channel, method, fake_call = _mock_grpc_objects(empty_pb2.Empty())
     client = operations_v1.OperationsAsyncClient(mocked_channel)
 
-    await client.delete_operation("name", metadata=[("header", "foo")])
+    await client.delete_operation(
+        "name", metadata=[("header", "foo")], compression=Compression.Gzip
+    )
 
     assert method.call_count == 1
     assert tuple(method.call_args_list[0])[0][0].name == "name"
     assert ("header", "foo") in tuple(method.call_args_list[0])[1]["metadata"]
+    assert tuple(method.call_args_list[0])[1]["compression"] == Compression.Gzip
     assert ("x-goog-request-params", "name=name") in tuple(method.call_args_list[0])[1][
         "metadata"
     ]
@@ -97,11 +113,14 @@ async def test_cancel_operation():
     mocked_channel, method, fake_call = _mock_grpc_objects(empty_pb2.Empty())
     client = operations_v1.OperationsAsyncClient(mocked_channel)
 
-    await client.cancel_operation("name", metadata=[("header", "foo")])
+    await client.cancel_operation(
+        "name", metadata=[("header", "foo")], compression=Compression.Gzip
+    )
 
     assert method.call_count == 1
     assert tuple(method.call_args_list[0])[0][0].name == "name"
     assert ("header", "foo") in tuple(method.call_args_list[0])[1]["metadata"]
+    assert tuple(method.call_args_list[0])[1]["compression"] == Compression.Gzip
     assert ("x-goog-request-params", "name=name") in tuple(method.call_args_list[0])[1][
         "metadata"
     ]
diff --git a/tests/asyncio/retry/__init__.py b/tests/asyncio/retry/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/asyncio/retry/test_retry_streaming_async.py b/tests/asyncio/retry/test_retry_streaming_async.py
new file mode 100644
index 00000000..e44f5361
--- /dev/null
+++ b/tests/asyncio/retry/test_retry_streaming_async.py
@@ -0,0 +1,601 @@
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import asyncio
+import datetime
+import re
+
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock  # pragma: NO COVER  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    import mock  # type: ignore
+
+import pytest
+
+from google.api_core import exceptions
+from google.api_core import retry_async
+from google.api_core.retry import retry_streaming_async
+
+from ...unit.retry.test_retry_base import Test_BaseRetry
+
+
+@pytest.mark.asyncio
+async def test_retry_streaming_target_bad_sleep_generator():
+    from google.api_core.retry.retry_streaming_async import retry_target_stream
+
+    with pytest.raises(ValueError, match="Sleep generator"):
+        await retry_target_stream(None, lambda x: True, [], None).__anext__()
+
+
+@mock.patch("asyncio.sleep", autospec=True)
+@pytest.mark.asyncio
+async def test_retry_streaming_target_dynamic_backoff(sleep):
+    """
+    sleep_generator should be iterated after on_error, to support dynamic backoff
+    """
+    from functools import partial
+    from google.api_core.retry.retry_streaming_async import retry_target_stream
+
+    sleep.side_effect = RuntimeError("stop after sleep")
+    # start with empty sleep generator; values are added after exception in push_sleep_value
+    sleep_values = []
+    error_target = partial(TestAsyncStreamingRetry._generator_mock, error_on=0)
+    inserted_sleep = 99
+
+    def push_sleep_value(err):
+        sleep_values.append(inserted_sleep)
+
+    with pytest.raises(RuntimeError):
+        await retry_target_stream(
+            error_target,
+            predicate=lambda x: True,
+            sleep_generator=sleep_values,
+            on_error=push_sleep_value,
+        ).__anext__()
+    assert sleep.call_count == 1
+    sleep.assert_called_once_with(inserted_sleep)
+
+
+class TestAsyncStreamingRetry(Test_BaseRetry):
+    def _make_one(self, *args, **kwargs):
+        return retry_streaming_async.AsyncStreamingRetry(*args, **kwargs)
+
+    def test___str__(self):
+        def if_exception_type(exc):
+            return bool(exc)  # pragma: NO COVER
+
+        # Explicitly set all attributes as changed Retry defaults should not
+        # cause this test to start failing.
+        retry_ = retry_streaming_async.AsyncStreamingRetry(
+            predicate=if_exception_type,
+            initial=1.0,
+            maximum=60.0,
+            multiplier=2.0,
+            timeout=120.0,
+            on_error=None,
+        )
+        assert re.match(
+            (
+                r"<AsyncStreamingRetry predicate=<function.*?if_exception_type.*?>, "
+                r"initial=1.0, maximum=60.0, multiplier=2.0, timeout=120.0, "
+                r"on_error=None>"
+            ),
+            str(retry_),
+        )
+
+    @staticmethod
+    async def _generator_mock(
+        num=5,
+        error_on=None,
+        exceptions_seen=None,
+        sleep_time=0,
+    ):
+        """
+        Helper to create a mock generator that yields a number of values
+        Generator can optionally raise an exception on a specific iteration
+
+        Args:
+          - num (int): the number of values to yield
+          - error_on (int): if given, the generator will raise a ValueError on the specified iteration
+          - exceptions_seen (list): if given, the generator will append any exceptions to this list before raising
+          - sleep_time (int): if given, the generator will asyncio.sleep for this many seconds before yielding each value
+        """
+        try:
+            for i in range(num):
+                if sleep_time:
+                    await asyncio.sleep(sleep_time)
+                if error_on is not None and i == error_on:
+                    raise ValueError("generator mock error")
+                yield i
+        except (Exception, BaseException, GeneratorExit) as e:
+            # keep track of exceptions seen by generator
+            if exceptions_seen is not None:
+                exceptions_seen.append(e)
+            raise
+
+    @mock.patch("asyncio.sleep", autospec=True)
+    @pytest.mark.asyncio
+    async def test___call___generator_success(self, sleep):
+        """
+        Test that a retry-decorated generator yields values as expected
+        This test checks a generator with no issues
+        """
+        from collections.abc import AsyncGenerator
+
+        retry_ = retry_streaming_async.AsyncStreamingRetry()
+        decorated = retry_(self._generator_mock)
+
+        num = 10
+        generator = await decorated(num)
+        # check types
+        assert isinstance(generator, AsyncGenerator)
+        assert isinstance(self._generator_mock(num), AsyncGenerator)
+        # check yield contents
+        unpacked = [i async for i in generator]
+        assert len(unpacked) == num
+        expected = [i async for i in self._generator_mock(num)]
+        for a, b in zip(unpacked, expected):
+            assert a == b
+        sleep.assert_not_called()
+
+    @mock.patch("asyncio.sleep", autospec=True)
+    @pytest.mark.asyncio
+    async def test___call___generator_retry(self, sleep):
+        """
+        Tests that a retry-decorated generator will retry on errors
+        """
+        on_error = mock.Mock(return_value=None)
+        retry_ = retry_streaming_async.AsyncStreamingRetry(
+            on_error=on_error,
+            predicate=retry_async.if_exception_type(ValueError),
+            timeout=None,
+        )
+        generator = await retry_(self._generator_mock)(error_on=3)
+        # error thrown on 3
+        # generator should contain 0, 1, 2 looping
+        unpacked = [await generator.__anext__() for i in range(10)]
+        assert unpacked == [0, 1, 2, 0, 1, 2, 0, 1, 2, 0]
+        assert on_error.call_count == 3
+        await generator.aclose()
+
+    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n)
+    @mock.patch("asyncio.sleep", autospec=True)
+    @pytest.mark.parametrize("use_deadline_arg", [True, False])
+    @pytest.mark.asyncio
+    async def test___call___generator_retry_hitting_timeout(
+        self, sleep, uniform, use_deadline_arg
+    ):
+        """
+        Tests that a retry-decorated generator will throw a RetryError
+        after using the time budget
+        """
+        import time
+
+        timeout_val = 9.9
+        # support "deadline" as an alias for "timeout"
+        timeout_kwarg = (
+            {"timeout": timeout_val}
+            if not use_deadline_arg
+            else {"deadline": timeout_val}
+        )
+
+        on_error = mock.Mock()
+        retry_ = retry_streaming_async.AsyncStreamingRetry(
+            predicate=retry_async.if_exception_type(ValueError),
+            initial=1.0,
+            maximum=1024.0,
+            multiplier=2.0,
+            **timeout_kwarg,
+        )
+
+        time_now = time.monotonic()
+        now_patcher = mock.patch(
+            "time.monotonic",
+            return_value=time_now,
+        )
+
+        decorated = retry_(self._generator_mock, on_error=on_error)
+        generator = await decorated(error_on=1)
+
+        with now_patcher as patched_now:
+            # Make sure that calls to fake asyncio.sleep() also advance the mocked
+            # time clock.
+            def increase_time(sleep_delay):
+                patched_now.return_value += sleep_delay
+
+            sleep.side_effect = increase_time
+
+            with pytest.raises(exceptions.RetryError):
+                [i async for i in generator]
+
+        assert on_error.call_count == 4
+        # check the delays
+        assert sleep.call_count == 3  # once between each successive target calls
+        last_wait = sleep.call_args.args[0]
+        total_wait = sum(call_args.args[0] for call_args in sleep.call_args_list)
+        # next wait would have put us over, so ended early
+        assert last_wait == 4
+        assert total_wait == 7
+
+    @pytest.mark.asyncio
+    async def test___call___generator_cancellations(self):
+        """
+        cancel calls should propagate to the generator
+        """
+        # test without cancel as retryable
+        retry_ = retry_streaming_async.AsyncStreamingRetry()
+        utcnow = datetime.datetime.now(datetime.timezone.utc)
+        mock.patch("google.api_core.datetime_helpers.utcnow", return_value=utcnow)
+        generator = await retry_(self._generator_mock)(sleep_time=0.2)
+        assert await generator.__anext__() == 0
+        task = asyncio.create_task(generator.__anext__())
+        task.cancel()
+        with pytest.raises(asyncio.CancelledError):
+            await task
+        with pytest.raises(StopAsyncIteration):
+            await generator.__anext__()
+
+    @mock.patch("asyncio.sleep", autospec=True)
+    @pytest.mark.asyncio
+    async def test___call___with_generator_send(self, sleep):
+        """
+        Send should be passed through retry into target generator
+        """
+
+        async def _mock_send_gen():
+            """
+            always yield whatever was sent in
+            """
+            in_ = yield
+            while True:
+                in_ = yield in_
+
+        retry_ = retry_streaming_async.AsyncStreamingRetry()
+
+        decorated = retry_(_mock_send_gen)
+
+        generator = await decorated()
+        result = await generator.__anext__()
+        # first yield should be None
+        assert result is None
+        in_messages = ["test_1", "hello", "world"]
+        out_messages = []
+        for msg in in_messages:
+            recv = await generator.asend(msg)
+            out_messages.append(recv)
+        assert in_messages == out_messages
+        await generator.aclose()
+
+    @mock.patch("asyncio.sleep", autospec=True)
+    @pytest.mark.asyncio
+    async def test___call___generator_send_retry(self, sleep):
+        """
+        Send should be retried if target generator raises an error
+        """
+        on_error = mock.Mock(return_value=None)
+        retry_ = retry_streaming_async.AsyncStreamingRetry(
+            on_error=on_error,
+            predicate=retry_async.if_exception_type(ValueError),
+            timeout=None,
+        )
+        generator = await retry_(self._generator_mock)(error_on=3)
+        with pytest.raises(TypeError) as exc_info:
+            await generator.asend("cannot send to fresh generator")
+            assert exc_info.match("can't send non-None value")
+        await generator.aclose()
+
+        # error thrown on 3
+        # generator should contain 0, 1, 2 looping
+        generator = await retry_(self._generator_mock)(error_on=3)
+        assert await generator.__anext__() == 0
+        unpacked = [await generator.asend(i) for i in range(10)]
+        assert unpacked == [1, 2, 0, 1, 2, 0, 1, 2, 0, 1]
+        assert on_error.call_count == 3
+        await generator.aclose()
+
+    @mock.patch("asyncio.sleep", autospec=True)
+    @pytest.mark.asyncio
+    async def test___call___with_generator_close(self, sleep):
+        """
+        Close should be passed through retry into target generator
+        """
+        retry_ = retry_streaming_async.AsyncStreamingRetry()
+        decorated = retry_(self._generator_mock)
+        exception_list = []
+        generator = await decorated(10, exceptions_seen=exception_list)
+        for i in range(2):
+            await generator.__anext__()
+        await generator.aclose()
+
+        assert isinstance(exception_list[0], GeneratorExit)
+        with pytest.raises(StopAsyncIteration):
+            # calling next on closed generator should raise error
+            await generator.__anext__()
+
+    @mock.patch("asyncio.sleep", autospec=True)
+    @pytest.mark.asyncio
+    async def test___call___with_new_generator_close(self, sleep):
+        """
+        Close should be passed through retry into target generator,
+        even when it hasn't been iterated yet
+        """
+        retry_ = retry_streaming_async.AsyncStreamingRetry()
+        decorated = retry_(self._generator_mock)
+        exception_list = []
+        generator = await decorated(10, exceptions_seen=exception_list)
+        await generator.aclose()
+
+        with pytest.raises(StopAsyncIteration):
+            # calling next on closed generator should raise error
+            await generator.__anext__()
+
+    @mock.patch("asyncio.sleep", autospec=True)
+    @pytest.mark.asyncio
+    async def test___call___with_generator_throw(self, sleep):
+        """
+        Throw should be passed through retry into target generator
+        """
+
+        # The generator should not retry when it encounters a non-retryable error
+        retry_ = retry_streaming_async.AsyncStreamingRetry(
+            predicate=retry_async.if_exception_type(ValueError),
+        )
+        decorated = retry_(self._generator_mock)
+        exception_list = []
+        generator = await decorated(10, exceptions_seen=exception_list)
+        for i in range(2):
+            await generator.__anext__()
+        with pytest.raises(BufferError):
+            await generator.athrow(BufferError("test"))
+        assert isinstance(exception_list[0], BufferError)
+        with pytest.raises(StopAsyncIteration):
+            # calling next on closed generator should raise error
+            await generator.__anext__()
+
+        # In contrast, the generator should retry if we throw a retryable exception
+        exception_list = []
+        generator = await decorated(10, exceptions_seen=exception_list)
+        for i in range(2):
+            await generator.__anext__()
+        throw_val = await generator.athrow(ValueError("test"))
+        assert throw_val == 0
+        assert isinstance(exception_list[0], ValueError)
+        # calling next on generator should not raise error, because it was retried
+        assert await generator.__anext__() == 1
+
+    @pytest.mark.parametrize("awaitable_wrapped", [True, False])
+    @mock.patch("asyncio.sleep", autospec=True)
+    @pytest.mark.asyncio
+    async def test___call___with_iterable_send(self, sleep, awaitable_wrapped):
+        """
+        Send should work like next if the wrapped iterable does not support it
+        """
+        retry_ = retry_streaming_async.AsyncStreamingRetry()
+
+        def iterable_fn():
+            class CustomIterable:
+                def __init__(self):
+                    self.i = -1
+
+                def __aiter__(self):
+                    return self
+
+                async def __anext__(self):
+                    self.i += 1
+                    return self.i
+
+            return CustomIterable()
+
+        if awaitable_wrapped:
+
+            async def wrapper():
+                return iterable_fn()
+
+            decorated = retry_(wrapper)
+        else:
+            decorated = retry_(iterable_fn)
+
+        retryable = await decorated()
+        # initiate the generator by calling next
+        result = await retryable.__anext__()
+        assert result == 0
+        # test sending values
+        assert await retryable.asend("test") == 1
+        assert await retryable.asend("test2") == 2
+        assert await retryable.asend("test3") == 3
+        await retryable.aclose()
+
+    @pytest.mark.parametrize("awaitable_wrapped", [True, False])
+    @mock.patch("asyncio.sleep", autospec=True)
+    @pytest.mark.asyncio
+    async def test___call___with_iterable_close(self, sleep, awaitable_wrapped):
+        """
+        close should be handled by wrapper if wrapped iterable does not support it
+        """
+        retry_ = retry_streaming_async.AsyncStreamingRetry()
+
+        def iterable_fn():
+            class CustomIterable:
+                def __init__(self):
+                    self.i = -1
+
+                def __aiter__(self):
+                    return self
+
+                async def __anext__(self):
+                    self.i += 1
+                    return self.i
+
+            return CustomIterable()
+
+        if awaitable_wrapped:
+
+            async def wrapper():
+                return iterable_fn()
+
+            decorated = retry_(wrapper)
+        else:
+            decorated = retry_(iterable_fn)
+
+        # try closing active generator
+        retryable = await decorated()
+        assert await retryable.__anext__() == 0
+        await retryable.aclose()
+        with pytest.raises(StopAsyncIteration):
+            await retryable.__anext__()
+        # try closing new generator
+        new_retryable = await decorated()
+        await new_retryable.aclose()
+        with pytest.raises(StopAsyncIteration):
+            await new_retryable.__anext__()
+
+    @pytest.mark.parametrize("awaitable_wrapped", [True, False])
+    @mock.patch("asyncio.sleep", autospec=True)
+    @pytest.mark.asyncio
+    async def test___call___with_iterable_throw(self, sleep, awaitable_wrapped):
+        """
+        Throw should work even if the wrapped iterable does not support it
+        """
+
+        predicate = retry_async.if_exception_type(ValueError)
+        retry_ = retry_streaming_async.AsyncStreamingRetry(predicate=predicate)
+
+        def iterable_fn():
+            class CustomIterable:
+                def __init__(self):
+                    self.i = -1
+
+                def __aiter__(self):
+                    return self
+
+                async def __anext__(self):
+                    self.i += 1
+                    return self.i
+
+            return CustomIterable()
+
+        if awaitable_wrapped:
+
+            async def wrapper():
+                return iterable_fn()
+
+            decorated = retry_(wrapper)
+        else:
+            decorated = retry_(iterable_fn)
+
+        # try throwing with active generator
+        retryable = await decorated()
+        assert await retryable.__anext__() == 0
+        # should swallow errors in predicate
+        await retryable.athrow(ValueError("test"))
+        # should raise errors not in predicate
+        with pytest.raises(BufferError):
+            await retryable.athrow(BufferError("test"))
+        with pytest.raises(StopAsyncIteration):
+            await retryable.__anext__()
+        # try throwing with new generator
+        new_retryable = await decorated()
+        with pytest.raises(BufferError):
+            await new_retryable.athrow(BufferError("test"))
+        with pytest.raises(StopAsyncIteration):
+            await new_retryable.__anext__()
+
+    @pytest.mark.asyncio
+    async def test_exc_factory_non_retryable_error(self):
+        """
+        generator should give the option to override exception creation logic
+        test when non-retryable error is thrown
+        """
+        from google.api_core.retry import RetryFailureReason
+        from google.api_core.retry.retry_streaming_async import retry_target_stream
+
+        timeout = 6
+        sent_errors = [ValueError("test"), ValueError("test2"), BufferError("test3")]
+        expected_final_err = RuntimeError("done")
+        expected_source_err = ZeroDivisionError("test4")
+
+        def factory(*args, **kwargs):
+            assert len(kwargs) == 0
+            assert args[0] == sent_errors
+            assert args[1] == RetryFailureReason.NON_RETRYABLE_ERROR
+            assert args[2] == timeout
+            return expected_final_err, expected_source_err
+
+        generator = retry_target_stream(
+            self._generator_mock,
+            retry_async.if_exception_type(ValueError),
+            [0] * 3,
+            timeout=timeout,
+            exception_factory=factory,
+        )
+        # initialize the generator
+        await generator.__anext__()
+        # trigger some retryable errors
+        await generator.athrow(sent_errors[0])
+        await generator.athrow(sent_errors[1])
+        # trigger a non-retryable error
+        with pytest.raises(expected_final_err.__class__) as exc_info:
+            await generator.athrow(sent_errors[2])
+        assert exc_info.value == expected_final_err
+        assert exc_info.value.__cause__ == expected_source_err
+
+    @pytest.mark.asyncio
+    async def test_exc_factory_timeout(self):
+        """
+        generator should give the option to override exception creation logic
+        test when timeout is exceeded
+        """
+        import time
+        from google.api_core.retry import RetryFailureReason
+        from google.api_core.retry.retry_streaming_async import retry_target_stream
+
+        timeout = 2
+        time_now = time.monotonic()
+        now_patcher = mock.patch(
+            "time.monotonic",
+            return_value=time_now,
+        )
+
+        with now_patcher as patched_now:
+            timeout = 2
+            sent_errors = [ValueError("test"), ValueError("test2"), ValueError("test3")]
+            expected_final_err = RuntimeError("done")
+            expected_source_err = ZeroDivisionError("test4")
+
+            def factory(*args, **kwargs):
+                assert len(kwargs) == 0
+                assert args[0] == sent_errors
+                assert args[1] == RetryFailureReason.TIMEOUT
+                assert args[2] == timeout
+                return expected_final_err, expected_source_err
+
+            generator = retry_target_stream(
+                self._generator_mock,
+                retry_async.if_exception_type(ValueError),
+                [0] * 3,
+                timeout=timeout,
+                exception_factory=factory,
+            )
+            # initialize the generator
+            await generator.__anext__()
+            # trigger some retryable errors
+            await generator.athrow(sent_errors[0])
+            await generator.athrow(sent_errors[1])
+            # trigger a timeout
+            patched_now.return_value += timeout + 1
+            with pytest.raises(expected_final_err.__class__) as exc_info:
+                await generator.athrow(sent_errors[2])
+            assert exc_info.value == expected_final_err
+            assert exc_info.value.__cause__ == expected_source_err
diff --git a/tests/asyncio/test_retry_async.py b/tests/asyncio/retry/test_retry_unary_async.py
similarity index 62%
rename from tests/asyncio/test_retry_async.py
rename to tests/asyncio/retry/test_retry_unary_async.py
index 9e51044b..e7fdc963 100644
--- a/tests/asyncio/test_retry_async.py
+++ b/tests/asyncio/retry/test_retry_unary_async.py
@@ -15,12 +15,18 @@
 import datetime
 import re
 
-import mock
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock  # pragma: NO COVER  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    import mock  # type: ignore
 import pytest
 
 from google.api_core import exceptions
 from google.api_core import retry_async
 
+from ...unit.retry.test_retry_base import Test_BaseRetry
+
 
 @mock.patch("asyncio.sleep", autospec=True)
 @mock.patch(
@@ -97,140 +103,72 @@ async def test_retry_target_non_retryable_error(utcnow, sleep):
 
 
 @mock.patch("asyncio.sleep", autospec=True)
-@mock.patch("google.api_core.datetime_helpers.utcnow", autospec=True)
+@mock.patch("time.monotonic", autospec=True)
+@pytest.mark.parametrize("use_deadline_arg", [True, False])
 @pytest.mark.asyncio
-async def test_retry_target_deadline_exceeded(utcnow, sleep):
+async def test_retry_target_timeout_exceeded(monotonic, sleep, use_deadline_arg):
     predicate = retry_async.if_exception_type(ValueError)
     exception = ValueError("meep")
     target = mock.Mock(side_effect=exception)
     # Setup the timeline so that the first call takes 5 seconds but the second
-    # call takes 6, which puts the retry over the deadline.
-    utcnow.side_effect = [
-        # The first call to utcnow establishes the start of the timeline.
-        datetime.datetime.min,
-        datetime.datetime.min + datetime.timedelta(seconds=5),
-        datetime.datetime.min + datetime.timedelta(seconds=11),
-    ]
+    # call takes 6, which puts the retry over the timeout.
+    monotonic.side_effect = [0, 5, 11]
+
+    timeout_val = 10
+    # support "deadline" as an alias for "timeout"
+    timeout_kwarg = (
+        {"timeout": timeout_val} if not use_deadline_arg else {"deadline": timeout_val}
+    )
 
     with pytest.raises(exceptions.RetryError) as exc_info:
-        await retry_async.retry_target(target, predicate, range(10), deadline=10)
+        await retry_async.retry_target(target, predicate, range(10), **timeout_kwarg)
 
     assert exc_info.value.cause == exception
-    assert exc_info.match("Deadline of 10.0s exceeded")
+    assert exc_info.match("Timeout of 10.0s exceeded")
     assert exc_info.match("last exception: meep")
     assert target.call_count == 2
 
+    # Ensure the exception message does not include the target fn:
+    # it may be a partial with user data embedded
+    assert str(target) not in exc_info.exconly()
+
 
 @pytest.mark.asyncio
 async def test_retry_target_bad_sleep_generator():
     with pytest.raises(ValueError, match="Sleep generator"):
-        await retry_async.retry_target(
-            mock.sentinel.target, mock.sentinel.predicate, [], None
-        )
-
+        await retry_async.retry_target(mock.sentinel.target, lambda x: True, [], None)
 
-class TestAsyncRetry:
-    def test_constructor_defaults(self):
-        retry_ = retry_async.AsyncRetry()
-        assert retry_._predicate == retry_async.if_transient_error
-        assert retry_._initial == 1
-        assert retry_._maximum == 60
-        assert retry_._multiplier == 2
-        assert retry_._deadline == 120
-        assert retry_._on_error is None
-
-    def test_constructor_options(self):
-        _some_function = mock.Mock()
-
-        retry_ = retry_async.AsyncRetry(
-            predicate=mock.sentinel.predicate,
-            initial=1,
-            maximum=2,
-            multiplier=3,
-            deadline=4,
-            on_error=_some_function,
-        )
-        assert retry_._predicate == mock.sentinel.predicate
-        assert retry_._initial == 1
-        assert retry_._maximum == 2
-        assert retry_._multiplier == 3
-        assert retry_._deadline == 4
-        assert retry_._on_error is _some_function
 
-    def test_with_deadline(self):
-        retry_ = retry_async.AsyncRetry(
-            predicate=mock.sentinel.predicate,
-            initial=1,
-            maximum=2,
-            multiplier=3,
-            deadline=4,
-            on_error=mock.sentinel.on_error,
-        )
-        new_retry = retry_.with_deadline(42)
-        assert retry_ is not new_retry
-        assert new_retry._deadline == 42
-
-        # the rest of the attributes should remain the same
-        assert new_retry._predicate is retry_._predicate
-        assert new_retry._initial == retry_._initial
-        assert new_retry._maximum == retry_._maximum
-        assert new_retry._multiplier == retry_._multiplier
-        assert new_retry._on_error is retry_._on_error
-
-    def test_with_predicate(self):
-        retry_ = retry_async.AsyncRetry(
-            predicate=mock.sentinel.predicate,
-            initial=1,
-            maximum=2,
-            multiplier=3,
-            deadline=4,
-            on_error=mock.sentinel.on_error,
-        )
-        new_retry = retry_.with_predicate(mock.sentinel.predicate)
-        assert retry_ is not new_retry
-        assert new_retry._predicate == mock.sentinel.predicate
-
-        # the rest of the attributes should remain the same
-        assert new_retry._deadline == retry_._deadline
-        assert new_retry._initial == retry_._initial
-        assert new_retry._maximum == retry_._maximum
-        assert new_retry._multiplier == retry_._multiplier
-        assert new_retry._on_error is retry_._on_error
-
-    def test_with_delay_noop(self):
-        retry_ = retry_async.AsyncRetry(
-            predicate=mock.sentinel.predicate,
-            initial=1,
-            maximum=2,
-            multiplier=3,
-            deadline=4,
-            on_error=mock.sentinel.on_error,
+@mock.patch("asyncio.sleep", autospec=True)
+@pytest.mark.asyncio
+async def test_retry_target_dynamic_backoff(sleep):
+    """
+    sleep_generator should be iterated after on_error, to support dynamic backoff
+    """
+    sleep.side_effect = RuntimeError("stop after sleep")
+    # start with empty sleep generator; values are added after exception in push_sleep_value
+    sleep_values = []
+    exception = ValueError("trigger retry")
+    error_target = mock.Mock(side_effect=exception)
+    inserted_sleep = 99
+
+    def push_sleep_value(err):
+        sleep_values.append(inserted_sleep)
+
+    with pytest.raises(RuntimeError):
+        await retry_async.retry_target(
+            error_target,
+            predicate=lambda x: True,
+            sleep_generator=sleep_values,
+            on_error=push_sleep_value,
         )
-        new_retry = retry_.with_delay()
-        assert retry_ is not new_retry
-        assert new_retry._initial == retry_._initial
-        assert new_retry._maximum == retry_._maximum
-        assert new_retry._multiplier == retry_._multiplier
+    assert sleep.call_count == 1
+    sleep.assert_called_once_with(inserted_sleep)
 
-    def test_with_delay(self):
-        retry_ = retry_async.AsyncRetry(
-            predicate=mock.sentinel.predicate,
-            initial=1,
-            maximum=2,
-            multiplier=3,
-            deadline=4,
-            on_error=mock.sentinel.on_error,
-        )
-        new_retry = retry_.with_delay(initial=1, maximum=2, multiplier=3)
-        assert retry_ is not new_retry
-        assert new_retry._initial == 1
-        assert new_retry._maximum == 2
-        assert new_retry._multiplier == 3
 
-        # the rest of the attributes should remain the same
-        assert new_retry._deadline == retry_._deadline
-        assert new_retry._predicate is retry_._predicate
-        assert new_retry._on_error is retry_._on_error
+class TestAsyncRetry(Test_BaseRetry):
+    def _make_one(self, *args, **kwargs):
+        return retry_async.AsyncRetry(*args, **kwargs)
 
     def test___str__(self):
         def if_exception_type(exc):
@@ -243,13 +181,13 @@ def if_exception_type(exc):
             initial=1.0,
             maximum=60.0,
             multiplier=2.0,
-            deadline=120.0,
+            timeout=120.0,
             on_error=None,
         )
         assert re.match(
             (
                 r"<AsyncRetry predicate=<function.*?if_exception_type.*?>, "
-                r"initial=1.0, maximum=60.0, multiplier=2.0, deadline=120.0, "
+                r"initial=1.0, maximum=60.0, multiplier=2.0, timeout=120.0, "
                 r"on_error=None>"
             ),
             str(retry_),
@@ -272,12 +210,10 @@ async def test___call___and_execute_success(self, sleep):
         target.assert_called_once_with("meep")
         sleep.assert_not_called()
 
-    # Make uniform return half of its maximum, which is the calculated sleep time.
-    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n / 2.0)
+    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n)
     @mock.patch("asyncio.sleep", autospec=True)
     @pytest.mark.asyncio
     async def test___call___and_execute_retry(self, sleep, uniform):
-
         on_error = mock.Mock(spec=["__call__"], side_effect=[None])
         retry_ = retry_async.AsyncRetry(
             predicate=retry_async.if_exception_type(ValueError)
@@ -298,25 +234,20 @@ async def test___call___and_execute_retry(self, sleep, uniform):
         sleep.assert_called_once_with(retry_._initial)
         assert on_error.call_count == 1
 
-    # Make uniform return half of its maximum, which is the calculated sleep time.
-    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n / 2.0)
+    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n)
     @mock.patch("asyncio.sleep", autospec=True)
     @pytest.mark.asyncio
-    async def test___call___and_execute_retry_hitting_deadline(self, sleep, uniform):
-
+    async def test___call___and_execute_retry_hitting_timeout(self, sleep, uniform):
         on_error = mock.Mock(spec=["__call__"], side_effect=[None] * 10)
         retry_ = retry_async.AsyncRetry(
             predicate=retry_async.if_exception_type(ValueError),
             initial=1.0,
             maximum=1024.0,
             multiplier=2.0,
-            deadline=9.9,
+            timeout=30.9,
         )
 
-        utcnow = datetime.datetime.utcnow()
-        utcnow_patcher = mock.patch(
-            "google.api_core.datetime_helpers.utcnow", return_value=utcnow
-        )
+        monotonic_patcher = mock.patch("time.monotonic", return_value=0)
 
         target = mock.AsyncMock(spec=["__call__"], side_effect=[ValueError()] * 10)
         # __name__ is needed by functools.partial.
@@ -325,11 +256,11 @@ async def test___call___and_execute_retry_hitting_deadline(self, sleep, uniform)
         decorated = retry_(target, on_error=on_error)
         target.assert_not_called()
 
-        with utcnow_patcher as patched_utcnow:
+        with monotonic_patcher as patched_monotonic:
             # Make sure that calls to fake asyncio.sleep() also advance the mocked
             # time clock.
             def increase_time(sleep_delay):
-                patched_utcnow.return_value += datetime.timedelta(seconds=sleep_delay)
+                patched_monotonic.return_value += sleep_delay
 
             sleep.side_effect = increase_time
 
@@ -345,8 +276,17 @@ def increase_time(sleep_delay):
         last_wait = sleep.call_args.args[0]
         total_wait = sum(call_args.args[0] for call_args in sleep.call_args_list)
 
-        assert last_wait == 2.9  # and not 8.0, because the last delay was shortened
-        assert total_wait == 9.9  # the same as the deadline
+        assert last_wait == 8.0
+        # Next attempt would be scheduled in 16 secs, 15 + 16 = 31 > 30.9, thus
+        # we do not even wait for it to be scheduled (30.9 is configured timeout).
+        # This changes the previous logic of shortening the last attempt to fit
+        # in the timeout. The previous logic was removed to make Python retry
+        # logic consistent with the other languages and to not disrupt the
+        # randomized retry delays distribution by artificially increasing a
+        # probability of scheduling two (instead of one) last attempts with very
+        # short delay between them, while the second retry having very low chance
+        # of succeeding anyways.
+        assert total_wait == 15.0
 
     @mock.patch("asyncio.sleep", autospec=True)
     @pytest.mark.asyncio
@@ -372,8 +312,7 @@ async def test___init___without_retry_executed(self, sleep):
         sleep.assert_not_called()
         _some_function.assert_not_called()
 
-    # Make uniform return half of its maximum, which is the calculated sleep time.
-    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n / 2.0)
+    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n)
     @mock.patch("asyncio.sleep", autospec=True)
     @pytest.mark.asyncio
     async def test___init___when_retry_is_executed(self, sleep, uniform):
diff --git a/tests/asyncio/test_grpc_helpers_async.py b/tests/asyncio/test_grpc_helpers_async.py
index a511ed46..aa8d5d10 100644
--- a/tests/asyncio/test_grpc_helpers_async.py
+++ b/tests/asyncio/test_grpc_helpers_async.py
@@ -12,10 +12,23 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import grpc
-from grpc.experimental import aio
-import mock
-import pytest
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock  # pragma: NO COVER  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    import mock  # type: ignore
+import pytest  # noqa: I202
+
+try:
+    import grpc
+    from grpc import aio
+except ImportError:  # pragma: NO COVER
+    grpc = aio = None
+
+
+if grpc is None:  # pragma: NO COVER
+    pytest.skip("No GRPC", allow_module_level=True)
+
 
 from google.api_core import exceptions
 from google.api_core import grpc_helpers_async
@@ -33,6 +46,9 @@ def code(self):
     def details(self):
         return None
 
+    def trailing_metadata(self):
+        return None
+
 
 @pytest.mark.asyncio
 async def test_wrap_unary_errors():
@@ -85,12 +101,40 @@ async def test_common_methods_in_wrapped_call():
     assert mock_call.wait_for_connection.call_count == 1
 
 
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "callable_type,expected_wrapper_type",
+    [
+        (grpc.aio.UnaryStreamMultiCallable, grpc_helpers_async._WrappedUnaryStreamCall),
+        (grpc.aio.StreamUnaryMultiCallable, grpc_helpers_async._WrappedStreamUnaryCall),
+        (
+            grpc.aio.StreamStreamMultiCallable,
+            grpc_helpers_async._WrappedStreamStreamCall,
+        ),
+    ],
+)
+async def test_wrap_errors_w_stream_type(callable_type, expected_wrapper_type):
+    class ConcreteMulticallable(callable_type):
+        def __call__(self, *args, **kwargs):
+            raise NotImplementedError("Should not be called")
+
+    with mock.patch.object(
+        grpc_helpers_async, "_wrap_stream_errors"
+    ) as wrap_stream_errors:
+        callable_ = ConcreteMulticallable()
+        grpc_helpers_async.wrap_errors(callable_)
+        assert wrap_stream_errors.call_count == 1
+        wrap_stream_errors.assert_called_once_with(callable_, expected_wrapper_type)
+
+
 @pytest.mark.asyncio
 async def test_wrap_stream_errors_unary_stream():
     mock_call = mock.Mock(aio.UnaryStreamCall, autospec=True)
     multicallable = mock.Mock(return_value=mock_call)
 
-    wrapped_callable = grpc_helpers_async._wrap_stream_errors(multicallable)
+    wrapped_callable = grpc_helpers_async._wrap_stream_errors(
+        multicallable, grpc_helpers_async._WrappedUnaryStreamCall
+    )
 
     await wrapped_callable(1, 2, three="four")
     multicallable.assert_called_once_with(1, 2, three="four")
@@ -102,7 +146,9 @@ async def test_wrap_stream_errors_stream_unary():
     mock_call = mock.Mock(aio.StreamUnaryCall, autospec=True)
     multicallable = mock.Mock(return_value=mock_call)
 
-    wrapped_callable = grpc_helpers_async._wrap_stream_errors(multicallable)
+    wrapped_callable = grpc_helpers_async._wrap_stream_errors(
+        multicallable, grpc_helpers_async._WrappedStreamUnaryCall
+    )
 
     await wrapped_callable(1, 2, three="four")
     multicallable.assert_called_once_with(1, 2, three="four")
@@ -114,24 +160,15 @@ async def test_wrap_stream_errors_stream_stream():
     mock_call = mock.Mock(aio.StreamStreamCall, autospec=True)
     multicallable = mock.Mock(return_value=mock_call)
 
-    wrapped_callable = grpc_helpers_async._wrap_stream_errors(multicallable)
+    wrapped_callable = grpc_helpers_async._wrap_stream_errors(
+        multicallable, grpc_helpers_async._WrappedStreamStreamCall
+    )
 
     await wrapped_callable(1, 2, three="four")
     multicallable.assert_called_once_with(1, 2, three="four")
     assert mock_call.wait_for_connection.call_count == 1
 
 
-@pytest.mark.asyncio
-async def test_wrap_stream_errors_type_error():
-    mock_call = mock.Mock()
-    multicallable = mock.Mock(return_value=mock_call)
-
-    wrapped_callable = grpc_helpers_async._wrap_stream_errors(multicallable)
-
-    with pytest.raises(TypeError):
-        await wrapped_callable()
-
-
 @pytest.mark.asyncio
 async def test_wrap_stream_errors_raised():
     grpc_error = RpcErrorImpl(grpc.StatusCode.INVALID_ARGUMENT)
@@ -139,7 +176,9 @@ async def test_wrap_stream_errors_raised():
     mock_call.wait_for_connection = mock.AsyncMock(side_effect=[grpc_error])
     multicallable = mock.Mock(return_value=mock_call)
 
-    wrapped_callable = grpc_helpers_async._wrap_stream_errors(multicallable)
+    wrapped_callable = grpc_helpers_async._wrap_stream_errors(
+        multicallable, grpc_helpers_async._WrappedStreamStreamCall
+    )
 
     with pytest.raises(exceptions.InvalidArgument):
         await wrapped_callable()
@@ -154,7 +193,9 @@ async def test_wrap_stream_errors_read():
     mock_call.read = mock.AsyncMock(side_effect=grpc_error)
     multicallable = mock.Mock(return_value=mock_call)
 
-    wrapped_callable = grpc_helpers_async._wrap_stream_errors(multicallable)
+    wrapped_callable = grpc_helpers_async._wrap_stream_errors(
+        multicallable, grpc_helpers_async._WrappedStreamStreamCall
+    )
 
     wrapped_call = await wrapped_callable(1, 2, three="four")
     multicallable.assert_called_once_with(1, 2, three="four")
@@ -177,7 +218,9 @@ async def test_wrap_stream_errors_aiter():
     mock_call.__aiter__ = mock.Mock(return_value=mocked_aiter)
     multicallable = mock.Mock(return_value=mock_call)
 
-    wrapped_callable = grpc_helpers_async._wrap_stream_errors(multicallable)
+    wrapped_callable = grpc_helpers_async._wrap_stream_errors(
+        multicallable, grpc_helpers_async._WrappedStreamStreamCall
+    )
     wrapped_call = await wrapped_callable()
 
     with pytest.raises(exceptions.InvalidArgument) as exc_info:
@@ -198,7 +241,9 @@ async def test_wrap_stream_errors_aiter_non_rpc_error():
     mock_call.__aiter__ = mock.Mock(return_value=mocked_aiter)
     multicallable = mock.Mock(return_value=mock_call)
 
-    wrapped_callable = grpc_helpers_async._wrap_stream_errors(multicallable)
+    wrapped_callable = grpc_helpers_async._wrap_stream_errors(
+        multicallable, grpc_helpers_async._WrappedStreamStreamCall
+    )
     wrapped_call = await wrapped_callable()
 
     with pytest.raises(TypeError) as exc_info:
@@ -212,7 +257,9 @@ async def test_wrap_stream_errors_aiter_called_multiple_times():
     mock_call = mock.Mock(aio.StreamStreamCall, autospec=True)
     multicallable = mock.Mock(return_value=mock_call)
 
-    wrapped_callable = grpc_helpers_async._wrap_stream_errors(multicallable)
+    wrapped_callable = grpc_helpers_async._wrap_stream_errors(
+        multicallable, grpc_helpers_async._WrappedStreamStreamCall
+    )
     wrapped_call = await wrapped_callable()
 
     assert wrapped_call.__aiter__() == wrapped_call.__aiter__()
@@ -227,7 +274,9 @@ async def test_wrap_stream_errors_write():
     mock_call.done_writing = mock.AsyncMock(side_effect=[None, grpc_error])
     multicallable = mock.Mock(return_value=mock_call)
 
-    wrapped_callable = grpc_helpers_async._wrap_stream_errors(multicallable)
+    wrapped_callable = grpc_helpers_async._wrap_stream_errors(
+        multicallable, grpc_helpers_async._WrappedStreamStreamCall
+    )
 
     wrapped_call = await wrapped_callable()
 
@@ -254,6 +303,28 @@ def test_wrap_errors_non_streaming(wrap_unary_errors):
     wrap_unary_errors.assert_called_once_with(callable_)
 
 
+def test_grpc_async_stream():
+    """
+    GrpcAsyncStream type should be both an AsyncIterator and a grpc.aio.Call.
+    """
+    instance = grpc_helpers_async.GrpcAsyncStream[int]()
+    assert isinstance(instance, grpc.aio.Call)
+    # should implement __aiter__ and __anext__
+    assert hasattr(instance, "__aiter__")
+    it = instance.__aiter__()
+    assert hasattr(it, "__anext__")
+
+
+def test_awaitable_grpc_call():
+    """
+    AwaitableGrpcCall type should be an Awaitable and a grpc.aio.Call.
+    """
+    instance = grpc_helpers_async.AwaitableGrpcCall()
+    assert isinstance(instance, grpc.aio.Call)
+    # should implement __await__
+    assert hasattr(instance, "__await__")
+
+
 @mock.patch("google.api_core.grpc_helpers_async._wrap_stream_errors")
 def test_wrap_errors_streaming(wrap_stream_errors):
     callable_ = mock.create_autospec(aio.UnaryStreamMultiCallable)
@@ -261,87 +332,151 @@ def test_wrap_errors_streaming(wrap_stream_errors):
     result = grpc_helpers_async.wrap_errors(callable_)
 
     assert result == wrap_stream_errors.return_value
-    wrap_stream_errors.assert_called_once_with(callable_)
+    wrap_stream_errors.assert_called_once_with(
+        callable_, grpc_helpers_async._WrappedUnaryStreamCall
+    )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@pytest.mark.parametrize(
+    "attempt_direct_path,target,expected_target",
+    [
+        (None, "example.com:443", "example.com:443"),
+        (False, "example.com:443", "example.com:443"),
+        (True, "example.com:443", "google-c2p:///example.com"),
+        (True, "dns:///example.com", "google-c2p:///example.com"),
+        (True, "another-c2p:///example.com", "another-c2p:///example.com"),
+    ],
+)
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch(
     "google.auth.default",
     autospec=True,
-    return_value=(mock.sentinel.credentials, mock.sentinel.projet),
+    return_value=(mock.sentinel.credentials, mock.sentinel.project),
 )
-@mock.patch("grpc.experimental.aio.secure_channel")
-def test_create_channel_implicit(grpc_secure_channel, default, composite_creds_call):
-    target = "example.com:443"
+@mock.patch("grpc.aio.secure_channel")
+def test_create_channel_implicit(
+    grpc_secure_channel,
+    google_auth_default,
+    composite_creds_call,
+    attempt_direct_path,
+    target,
+    expected_target,
+):
     composite_creds = composite_creds_call.return_value
 
-    channel = grpc_helpers_async.create_channel(target)
+    channel = grpc_helpers_async.create_channel(
+        target, attempt_direct_path=attempt_direct_path
+    )
 
     assert channel is grpc_secure_channel.return_value
 
-    default.assert_called_once_with(scopes=None, default_scopes=None)
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    google_auth_default.assert_called_once_with(scopes=None, default_scopes=None)
+    grpc_secure_channel.assert_called_once_with(
+        expected_target, composite_creds, compression=None
+    )
 
 
+@pytest.mark.parametrize(
+    "attempt_direct_path,target, expected_target",
+    [
+        (None, "example.com:443", "example.com:443"),
+        (False, "example.com:443", "example.com:443"),
+        (True, "example.com:443", "google-c2p:///example.com"),
+        (True, "dns:///example.com", "google-c2p:///example.com"),
+        (True, "another-c2p:///example.com", "another-c2p:///example.com"),
+    ],
+)
 @mock.patch("google.auth.transport.grpc.AuthMetadataPlugin", autospec=True)
 @mock.patch(
     "google.auth.transport.requests.Request",
     autospec=True,
     return_value=mock.sentinel.Request,
 )
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch(
     "google.auth.default",
     autospec=True,
-    return_value=(mock.sentinel.credentials, mock.sentinel.projet),
+    return_value=(mock.sentinel.credentials, mock.sentinel.project),
 )
-@mock.patch("grpc.experimental.aio.secure_channel")
+@mock.patch("grpc.aio.secure_channel")
 def test_create_channel_implicit_with_default_host(
-    grpc_secure_channel, default, composite_creds_call, request, auth_metadata_plugin
+    grpc_secure_channel,
+    google_auth_default,
+    composite_creds_call,
+    request,
+    auth_metadata_plugin,
+    attempt_direct_path,
+    target,
+    expected_target,
 ):
-    target = "example.com:443"
     default_host = "example.com"
     composite_creds = composite_creds_call.return_value
 
-    channel = grpc_helpers_async.create_channel(target, default_host=default_host)
+    channel = grpc_helpers_async.create_channel(
+        target, default_host=default_host, attempt_direct_path=attempt_direct_path
+    )
 
     assert channel is grpc_secure_channel.return_value
 
-    default.assert_called_once_with(scopes=None, default_scopes=None)
+    google_auth_default.assert_called_once_with(scopes=None, default_scopes=None)
     auth_metadata_plugin.assert_called_once_with(
         mock.sentinel.credentials, mock.sentinel.Request, default_host=default_host
     )
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    grpc_secure_channel.assert_called_once_with(
+        expected_target, composite_creds, compression=None
+    )
 
 
+@pytest.mark.parametrize(
+    "attempt_direct_path",
+    [
+        None,
+        False,
+    ],
+)
 @mock.patch("grpc.composite_channel_credentials")
 @mock.patch(
     "google.auth.default",
-    return_value=(mock.sentinel.credentials, mock.sentinel.projet),
+    return_value=(mock.sentinel.credentials, mock.sentinel.project),
 )
-@mock.patch("grpc.experimental.aio.secure_channel")
+@mock.patch("grpc.aio.secure_channel")
 def test_create_channel_implicit_with_ssl_creds(
-    grpc_secure_channel, default, composite_creds_call
+    grpc_secure_channel, default, composite_creds_call, attempt_direct_path
 ):
     target = "example.com:443"
 
     ssl_creds = grpc.ssl_channel_credentials()
 
-    grpc_helpers_async.create_channel(target, ssl_credentials=ssl_creds)
+    grpc_helpers_async.create_channel(
+        target, ssl_credentials=ssl_creds, attempt_direct_path=attempt_direct_path
+    )
 
     default.assert_called_once_with(scopes=None, default_scopes=None)
     composite_creds_call.assert_called_once_with(ssl_creds, mock.ANY)
     composite_creds = composite_creds_call.return_value
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    grpc_secure_channel.assert_called_once_with(
+        target, composite_creds, compression=None
+    )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+def test_create_channel_implicit_with_ssl_creds_attempt_direct_path_true():
+    target = "example.com:443"
+    ssl_creds = grpc.ssl_channel_credentials()
+    with pytest.raises(
+        ValueError, match="Using ssl_credentials with Direct Path is not supported"
+    ):
+        grpc_helpers_async.create_channel(
+            target, ssl_credentials=ssl_creds, attempt_direct_path=True
+        )
+
+
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch(
     "google.auth.default",
     autospec=True,
-    return_value=(mock.sentinel.credentials, mock.sentinel.projet),
+    return_value=(mock.sentinel.credentials, mock.sentinel.project),
 )
-@mock.patch("grpc.experimental.aio.secure_channel")
+@mock.patch("grpc.aio.secure_channel")
 def test_create_channel_implicit_with_scopes(
     grpc_secure_channel, default, composite_creds_call
 ):
@@ -353,16 +488,18 @@ def test_create_channel_implicit_with_scopes(
     assert channel is grpc_secure_channel.return_value
 
     default.assert_called_once_with(scopes=["one", "two"], default_scopes=None)
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    grpc_secure_channel.assert_called_once_with(
+        target, composite_creds, compression=None
+    )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch(
     "google.auth.default",
     autospec=True,
-    return_value=(mock.sentinel.credentials, mock.sentinel.projet),
+    return_value=(mock.sentinel.credentials, mock.sentinel.project),
 )
-@mock.patch("grpc.experimental.aio.secure_channel")
+@mock.patch("grpc.aio.secure_channel")
 def test_create_channel_implicit_with_default_scopes(
     grpc_secure_channel, default, composite_creds_call
 ):
@@ -370,13 +507,15 @@ def test_create_channel_implicit_with_default_scopes(
     composite_creds = composite_creds_call.return_value
 
     channel = grpc_helpers_async.create_channel(
-        target, default_scopes=["three", "four"]
+        target, default_scopes=["three", "four"], compression=grpc.Compression.Gzip
     )
 
     assert channel is grpc_secure_channel.return_value
 
     default.assert_called_once_with(scopes=None, default_scopes=["three", "four"])
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    grpc_secure_channel.assert_called_once_with(
+        target, composite_creds, compression=grpc.Compression.Gzip
+    )
 
 
 def test_create_channel_explicit_with_duplicate_credentials():
@@ -392,26 +531,28 @@ def test_create_channel_explicit_with_duplicate_credentials():
     assert "mutually exclusive" in str(excinfo.value)
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch("google.auth.credentials.with_scopes_if_required", autospec=True)
-@mock.patch("grpc.experimental.aio.secure_channel")
+@mock.patch("grpc.aio.secure_channel")
 def test_create_channel_explicit(grpc_secure_channel, auth_creds, composite_creds_call):
     target = "example.com:443"
     composite_creds = composite_creds_call.return_value
 
     channel = grpc_helpers_async.create_channel(
-        target, credentials=mock.sentinel.credentials
+        target, credentials=mock.sentinel.credentials, compression=grpc.Compression.Gzip
     )
 
     auth_creds.assert_called_once_with(
         mock.sentinel.credentials, scopes=None, default_scopes=None
     )
     assert channel is grpc_secure_channel.return_value
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    grpc_secure_channel.assert_called_once_with(
+        target, composite_creds, compression=grpc.Compression.Gzip
+    )
 
 
-@mock.patch("grpc.composite_channel_credentials")
-@mock.patch("grpc.experimental.aio.secure_channel")
+@mock.patch("grpc.compute_engine_channel_credentials")
+@mock.patch("grpc.aio.secure_channel")
 def test_create_channel_explicit_scoped(grpc_secure_channel, composite_creds_call):
     target = "example.com:443"
     scopes = ["1", "2"]
@@ -421,16 +562,21 @@ def test_create_channel_explicit_scoped(grpc_secure_channel, composite_creds_cal
     credentials.requires_scopes = True
 
     channel = grpc_helpers_async.create_channel(
-        target, credentials=credentials, scopes=scopes
+        target,
+        credentials=credentials,
+        scopes=scopes,
+        compression=grpc.Compression.Gzip,
     )
 
     credentials.with_scopes.assert_called_once_with(scopes, default_scopes=None)
     assert channel is grpc_secure_channel.return_value
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    grpc_secure_channel.assert_called_once_with(
+        target, composite_creds, compression=grpc.Compression.Gzip
+    )
 
 
-@mock.patch("grpc.composite_channel_credentials")
-@mock.patch("grpc.experimental.aio.secure_channel")
+@mock.patch("grpc.compute_engine_channel_credentials")
+@mock.patch("grpc.aio.secure_channel")
 def test_create_channel_explicit_default_scopes(
     grpc_secure_channel, composite_creds_call
 ):
@@ -442,18 +588,23 @@ def test_create_channel_explicit_default_scopes(
     credentials.requires_scopes = True
 
     channel = grpc_helpers_async.create_channel(
-        target, credentials=credentials, default_scopes=default_scopes
+        target,
+        credentials=credentials,
+        default_scopes=default_scopes,
+        compression=grpc.Compression.Gzip,
     )
 
     credentials.with_scopes.assert_called_once_with(
         scopes=None, default_scopes=default_scopes
     )
     assert channel is grpc_secure_channel.return_value
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    grpc_secure_channel.assert_called_once_with(
+        target, composite_creds, compression=grpc.Compression.Gzip
+    )
 
 
-@mock.patch("grpc.composite_channel_credentials")
-@mock.patch("grpc.experimental.aio.secure_channel")
+@mock.patch("grpc.compute_engine_channel_credentials")
+@mock.patch("grpc.aio.secure_channel")
 def test_create_channel_explicit_with_quota_project(
     grpc_secure_channel, composite_creds_call
 ):
@@ -470,17 +621,19 @@ def test_create_channel_explicit_with_quota_project(
 
     credentials.with_quota_project.assert_called_once_with("project-foo")
     assert channel is grpc_secure_channel.return_value
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    grpc_secure_channel.assert_called_once_with(
+        target, composite_creds, compression=None
+    )
 
 
-@mock.patch("grpc.composite_channel_credentials")
-@mock.patch("grpc.experimental.aio.secure_channel")
+@mock.patch("grpc.compute_engine_channel_credentials")
+@mock.patch("grpc.aio.secure_channel")
 @mock.patch(
     "google.auth.load_credentials_from_file",
     autospec=True,
     return_value=(mock.sentinel.credentials, mock.sentinel.project),
 )
-def test_create_channnel_with_credentials_file(
+def test_create_channel_with_credentials_file(
     load_credentials_from_file, grpc_secure_channel, composite_creds_call
 ):
     target = "example.com:443"
@@ -496,11 +649,13 @@ def test_create_channnel_with_credentials_file(
         credentials_file, scopes=None, default_scopes=None
     )
     assert channel is grpc_secure_channel.return_value
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    grpc_secure_channel.assert_called_once_with(
+        target, composite_creds, compression=None
+    )
 
 
-@mock.patch("grpc.composite_channel_credentials")
-@mock.patch("grpc.experimental.aio.secure_channel")
+@mock.patch("grpc.compute_engine_channel_credentials")
+@mock.patch("grpc.aio.secure_channel")
 @mock.patch(
     "google.auth.load_credentials_from_file",
     autospec=True,
@@ -523,11 +678,13 @@ def test_create_channel_with_credentials_file_and_scopes(
         credentials_file, scopes=scopes, default_scopes=None
     )
     assert channel is grpc_secure_channel.return_value
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    grpc_secure_channel.assert_called_once_with(
+        target, composite_creds, compression=None
+    )
 
 
-@mock.patch("grpc.composite_channel_credentials")
-@mock.patch("grpc.experimental.aio.secure_channel")
+@mock.patch("grpc.compute_engine_channel_credentials")
+@mock.patch("grpc.aio.secure_channel")
 @mock.patch(
     "google.auth.load_credentials_from_file",
     autospec=True,
@@ -550,14 +707,13 @@ def test_create_channel_with_credentials_file_and_default_scopes(
         credentials_file, scopes=None, default_scopes=default_scopes
     )
     assert channel is grpc_secure_channel.return_value
-    grpc_secure_channel.assert_called_once_with(target, composite_creds)
+    grpc_secure_channel.assert_called_once_with(
+        target, composite_creds, compression=None
+    )
 
 
-@pytest.mark.skipif(
-    grpc_helpers_async.HAS_GRPC_GCP, reason="grpc_gcp module not available"
-)
-@mock.patch("grpc.experimental.aio.secure_channel")
-def test_create_channel_without_grpc_gcp(grpc_secure_channel):
+@mock.patch("grpc.aio.secure_channel")
+def test_create_channel(grpc_secure_channel):
     target = "example.com:443"
     scopes = ["test_scope"]
 
diff --git a/tests/asyncio/test_operation_async.py b/tests/asyncio/test_operation_async.py
index 907cda7c..9d9fb5d2 100644
--- a/tests/asyncio/test_operation_async.py
+++ b/tests/asyncio/test_operation_async.py
@@ -13,9 +13,19 @@
 # limitations under the License.
 
 
-import mock
 import pytest
 
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock  # pragma: NO COVER  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    import mock  # type: ignore
+
+try:
+    import grpc  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    pytest.skip("No GRPC", allow_module_level=True)
+
 from google.api_core import exceptions
 from google.api_core import operation_async
 from google.api_core import operations_v1
@@ -74,6 +84,7 @@ async def test_constructor():
     assert await future.running()
 
 
+@pytest.mark.asyncio
 def test_metadata():
     expected_metadata = struct_pb2.Struct()
     future, _, _ = make_operation_future(
@@ -166,6 +177,7 @@ async def test_unexpected_result(unused_sleep):
     assert "Unexpected state" in "{!r}".format(exception)
 
 
+@pytest.mark.asyncio
 def test_from_gapic():
     operation_proto = make_operation_proto(done=True)
     operations_client = mock.create_autospec(
diff --git a/tests/asyncio/test_page_iterator_async.py b/tests/asyncio/test_page_iterator_async.py
index 75f9e1cf..63e26d02 100644
--- a/tests/asyncio/test_page_iterator_async.py
+++ b/tests/asyncio/test_page_iterator_async.py
@@ -14,7 +14,11 @@
 
 import inspect
 
-import mock
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock  # pragma: NO COVER  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    import mock  # type: ignore
 import pytest
 
 from google.api_core import page_iterator_async
@@ -106,6 +110,7 @@ async def test__page_aiter_increment(self):
         await page_aiter.__anext__()
 
         assert iterator.num_results == 1
+        await page_aiter.aclose()
 
     @pytest.mark.asyncio
     async def test__page_aiter_no_increment(self):
@@ -118,6 +123,7 @@ async def test__page_aiter_no_increment(self):
 
         # results should still be 0 after fetching a page.
         assert iterator.num_results == 0
+        await page_aiter.aclose()
 
     @pytest.mark.asyncio
     async def test__items_aiter(self):
diff --git a/tests/asyncio/test_rest_streaming_async.py b/tests/asyncio/test_rest_streaming_async.py
new file mode 100644
index 00000000..c9caa2b1
--- /dev/null
+++ b/tests/asyncio/test_rest_streaming_async.py
@@ -0,0 +1,378 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# TODO: set random.seed explicitly in each test function.
+# See related issue: https://github.com/googleapis/python-api-core/issues/689.
+
+import datetime
+import logging
+import random
+import time
+from typing import List, AsyncIterator
+
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock  # pragma: NO COVER  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    import mock  # type: ignore
+
+import pytest  # noqa: I202
+
+import proto
+
+try:
+    from google.auth.aio.transport import Response
+except ImportError:
+    pytest.skip(
+        "google-api-core[async_rest] is required to test asynchronous rest streaming.",
+        allow_module_level=True,
+    )
+
+from google.api_core import rest_streaming_async
+from google.api import http_pb2
+from google.api import httpbody_pb2
+
+
+from ..helpers import Composer, Song, EchoResponse, parse_responses
+
+
+__protobuf__ = proto.module(package=__name__)
+SEED = int(time.time())
+logging.info(f"Starting async rest streaming tests with random seed: {SEED}")
+random.seed(SEED)
+
+
+async def mock_async_gen(data, chunk_size=1):
+    for i in range(0, len(data)):  # pragma: NO COVER
+        chunk = data[i : i + chunk_size]
+        yield chunk.encode("utf-8")
+
+
+class ResponseMock(Response):
+    class _ResponseItr(AsyncIterator[bytes]):
+        def __init__(self, _response_bytes: bytes, random_split=False):
+            self._responses_bytes = _response_bytes
+            self._idx = 0
+            self._random_split = random_split
+
+        def __aiter__(self):
+            return self
+
+        async def __anext__(self):
+            if self._idx >= len(self._responses_bytes):
+                raise StopAsyncIteration
+            if self._random_split:
+                n = random.randint(1, len(self._responses_bytes[self._idx :]))
+            else:
+                n = 1
+            x = self._responses_bytes[self._idx : self._idx + n]
+            self._idx += n
+            return x
+
+    def __init__(
+        self,
+        responses: List[proto.Message],
+        response_cls,
+        random_split=False,
+    ):
+        self._responses = responses
+        self._random_split = random_split
+        self._response_message_cls = response_cls
+
+    def _parse_responses(self):
+        return parse_responses(self._response_message_cls, self._responses)
+
+    @property
+    async def headers(self):
+        raise NotImplementedError()
+
+    @property
+    async def status_code(self):
+        raise NotImplementedError()
+
+    async def close(self):
+        raise NotImplementedError()
+
+    async def content(self, chunk_size=None):
+        itr = self._ResponseItr(
+            self._parse_responses(), random_split=self._random_split
+        )
+        async for chunk in itr:
+            yield chunk
+
+    async def read(self):
+        raise NotImplementedError()
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "random_split,resp_message_is_proto_plus",
+    [(False, True), (False, False)],
+)
+async def test_next_simple(random_split, resp_message_is_proto_plus):
+    if resp_message_is_proto_plus:
+        response_type = EchoResponse
+        responses = [EchoResponse(content="hello world"), EchoResponse(content="yes")]
+    else:
+        response_type = httpbody_pb2.HttpBody
+        responses = [
+            httpbody_pb2.HttpBody(content_type="hello world"),
+            httpbody_pb2.HttpBody(content_type="yes"),
+        ]
+
+    resp = ResponseMock(
+        responses=responses, random_split=random_split, response_cls=response_type
+    )
+    itr = rest_streaming_async.AsyncResponseIterator(resp, response_type)
+    idx = 0
+    async for response in itr:
+        assert response == responses[idx]
+        idx += 1
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "random_split,resp_message_is_proto_plus",
+    [
+        (True, True),
+        (False, True),
+        (True, False),
+        (False, False),
+    ],
+)
+async def test_next_nested(random_split, resp_message_is_proto_plus):
+    if resp_message_is_proto_plus:
+        response_type = Song
+        responses = [
+            Song(title="some song", composer=Composer(given_name="some name")),
+            Song(title="another song", date_added=datetime.datetime(2021, 12, 17)),
+        ]
+    else:
+        # Although `http_pb2.HttpRule`` is used in the response, any response message
+        # can be used which meets this criteria for the test of having a nested field.
+        response_type = http_pb2.HttpRule
+        responses = [
+            http_pb2.HttpRule(
+                selector="some selector",
+                custom=http_pb2.CustomHttpPattern(kind="some kind"),
+            ),
+            http_pb2.HttpRule(
+                selector="another selector",
+                custom=http_pb2.CustomHttpPattern(path="some path"),
+            ),
+        ]
+    resp = ResponseMock(
+        responses=responses, random_split=random_split, response_cls=response_type
+    )
+    itr = rest_streaming_async.AsyncResponseIterator(resp, response_type)
+    idx = 0
+    async for response in itr:
+        assert response == responses[idx]
+        idx += 1
+    assert idx == len(responses)
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "random_split,resp_message_is_proto_plus",
+    [
+        (True, True),
+        (False, True),
+        (True, False),
+        (False, False),
+    ],
+)
+async def test_next_stress(random_split, resp_message_is_proto_plus):
+    n = 50
+    if resp_message_is_proto_plus:
+        response_type = Song
+        responses = [
+            Song(title="title_%d" % i, composer=Composer(given_name="name_%d" % i))
+            for i in range(n)
+        ]
+    else:
+        response_type = http_pb2.HttpRule
+        responses = [
+            http_pb2.HttpRule(
+                selector="selector_%d" % i,
+                custom=http_pb2.CustomHttpPattern(path="path_%d" % i),
+            )
+            for i in range(n)
+        ]
+    resp = ResponseMock(
+        responses=responses, random_split=random_split, response_cls=response_type
+    )
+    itr = rest_streaming_async.AsyncResponseIterator(resp, response_type)
+    idx = 0
+    async for response in itr:
+        assert response == responses[idx]
+        idx += 1
+    assert idx == n
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "random_split,resp_message_is_proto_plus",
+    [
+        (True, True),
+        (False, True),
+        (True, False),
+        (False, False),
+    ],
+)
+async def test_next_escaped_characters_in_string(
+    random_split, resp_message_is_proto_plus
+):
+    if resp_message_is_proto_plus:
+        response_type = Song
+        composer_with_relateds = Composer()
+        relateds = ["Artist A", "Artist B"]
+        composer_with_relateds.relateds = relateds
+
+        responses = [
+            Song(
+                title='ti"tle\nfoo\tbar{}', composer=Composer(given_name="name\n\n\n")
+            ),
+            Song(
+                title='{"this is weird": "totally"}',
+                composer=Composer(given_name="\\{}\\"),
+            ),
+            Song(title='\\{"key": ["value",]}\\', composer=composer_with_relateds),
+        ]
+    else:
+        response_type = http_pb2.Http
+        responses = [
+            http_pb2.Http(
+                rules=[
+                    http_pb2.HttpRule(
+                        selector='ti"tle\nfoo\tbar{}',
+                        custom=http_pb2.CustomHttpPattern(kind="name\n\n\n"),
+                    )
+                ]
+            ),
+            http_pb2.Http(
+                rules=[
+                    http_pb2.HttpRule(
+                        selector='{"this is weird": "totally"}',
+                        custom=http_pb2.CustomHttpPattern(kind="\\{}\\"),
+                    )
+                ]
+            ),
+            http_pb2.Http(
+                rules=[
+                    http_pb2.HttpRule(
+                        selector='\\{"key": ["value",]}\\',
+                        custom=http_pb2.CustomHttpPattern(kind="\\{}\\"),
+                    )
+                ]
+            ),
+        ]
+    resp = ResponseMock(
+        responses=responses, random_split=random_split, response_cls=response_type
+    )
+    itr = rest_streaming_async.AsyncResponseIterator(resp, response_type)
+    idx = 0
+    async for response in itr:
+        assert response == responses[idx]
+        idx += 1
+    assert idx == len(responses)
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("response_type", [EchoResponse, httpbody_pb2.HttpBody])
+async def test_next_not_array(response_type):
+
+    data = '{"hello": 0}'
+    with mock.patch.object(
+        ResponseMock, "content", return_value=mock_async_gen(data)
+    ) as mock_method:
+        resp = ResponseMock(responses=[], response_cls=response_type)
+        itr = rest_streaming_async.AsyncResponseIterator(resp, response_type)
+        with pytest.raises(ValueError):
+            await itr.__anext__()
+        mock_method.assert_called_once()
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("response_type", [EchoResponse, httpbody_pb2.HttpBody])
+async def test_cancel(response_type):
+    with mock.patch.object(
+        ResponseMock, "close", new_callable=mock.AsyncMock
+    ) as mock_method:
+        resp = ResponseMock(responses=[], response_cls=response_type)
+        itr = rest_streaming_async.AsyncResponseIterator(resp, response_type)
+        await itr.cancel()
+        mock_method.assert_called_once()
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("response_type", [EchoResponse, httpbody_pb2.HttpBody])
+async def test_iterator_as_context_manager(response_type):
+    with mock.patch.object(
+        ResponseMock, "close", new_callable=mock.AsyncMock
+    ) as mock_method:
+        resp = ResponseMock(responses=[], response_cls=response_type)
+        async with rest_streaming_async.AsyncResponseIterator(resp, response_type):
+            pass
+        mock_method.assert_called_once()
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize(
+    "response_type,return_value",
+    [
+        (EchoResponse, bytes('[{"content": "hello"}, {', "utf-8")),
+        (httpbody_pb2.HttpBody, bytes('[{"content_type": "hello"}, {', "utf-8")),
+    ],
+)
+async def test_check_buffer(response_type, return_value):
+    with mock.patch.object(
+        ResponseMock,
+        "_parse_responses",
+        return_value=return_value,
+    ):
+        resp = ResponseMock(responses=[], response_cls=response_type)
+        itr = rest_streaming_async.AsyncResponseIterator(resp, response_type)
+        with pytest.raises(ValueError):
+            await itr.__anext__()
+            await itr.__anext__()
+
+
+@pytest.mark.asyncio
+@pytest.mark.parametrize("response_type", [EchoResponse, httpbody_pb2.HttpBody])
+async def test_next_html(response_type):
+
+    data = "<!DOCTYPE html><html></html>"
+    with mock.patch.object(
+        ResponseMock, "content", return_value=mock_async_gen(data)
+    ) as mock_method:
+        resp = ResponseMock(responses=[], response_cls=response_type)
+
+        itr = rest_streaming_async.AsyncResponseIterator(resp, response_type)
+        with pytest.raises(ValueError):
+            await itr.__anext__()
+        mock_method.assert_called_once()
+
+
+@pytest.mark.asyncio
+async def test_invalid_response_class():
+    class SomeClass:
+        pass
+
+    resp = ResponseMock(responses=[], response_cls=SomeClass)
+    with pytest.raises(
+        ValueError,
+        match="Response message class must be a subclass of proto.Message or google.protobuf.message.Message",
+    ):
+        rest_streaming_async.AsyncResponseIterator(resp, SomeClass)
diff --git a/tests/helpers.py b/tests/helpers.py
new file mode 100644
index 00000000..3429d511
--- /dev/null
+++ b/tests/helpers.py
@@ -0,0 +1,71 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helpers for tests"""
+
+import logging
+from typing import List
+
+import proto
+
+from google.protobuf import duration_pb2
+from google.protobuf import timestamp_pb2
+from google.protobuf.json_format import MessageToJson
+
+
+class Genre(proto.Enum):
+    GENRE_UNSPECIFIED = 0
+    CLASSICAL = 1
+    JAZZ = 2
+    ROCK = 3
+
+
+class Composer(proto.Message):
+    given_name = proto.Field(proto.STRING, number=1)
+    family_name = proto.Field(proto.STRING, number=2)
+    relateds = proto.RepeatedField(proto.STRING, number=3)
+    indices = proto.MapField(proto.STRING, proto.STRING, number=4)
+
+
+class Song(proto.Message):
+    composer = proto.Field(Composer, number=1)
+    title = proto.Field(proto.STRING, number=2)
+    lyrics = proto.Field(proto.STRING, number=3)
+    year = proto.Field(proto.INT32, number=4)
+    genre = proto.Field(Genre, number=5)
+    is_five_mins_longer = proto.Field(proto.BOOL, number=6)
+    score = proto.Field(proto.DOUBLE, number=7)
+    likes = proto.Field(proto.INT64, number=8)
+    duration = proto.Field(duration_pb2.Duration, number=9)
+    date_added = proto.Field(timestamp_pb2.Timestamp, number=10)
+
+
+class EchoResponse(proto.Message):
+    content = proto.Field(proto.STRING, number=1)
+
+
+def parse_responses(response_message_cls, all_responses: List[proto.Message]) -> bytes:
+    # json.dumps returns a string surrounded with quotes that need to be stripped
+    # in order to be an actual JSON.
+    json_responses = [
+        (
+            response_message_cls.to_json(response).strip('"')
+            if issubclass(response_message_cls, proto.Message)
+            else MessageToJson(response).strip('"')
+        )
+        for response in all_responses
+    ]
+    logging.info(f"Sending JSON stream: {json_responses}")
+    ret_val = "[{}]".format(",".join(json_responses))
+    return bytes(ret_val, "utf-8")
diff --git a/tests/unit/future/test__helpers.py b/tests/unit/future/test__helpers.py
index 98afc599..a37efdd4 100644
--- a/tests/unit/future/test__helpers.py
+++ b/tests/unit/future/test__helpers.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import mock
+from unittest import mock
 
 from google.api_core.future import _helpers
 
diff --git a/tests/unit/future/test_polling.py b/tests/unit/future/test_polling.py
index 2381d036..2f66f230 100644
--- a/tests/unit/future/test_polling.py
+++ b/tests/unit/future/test_polling.py
@@ -15,8 +15,8 @@
 import concurrent.futures
 import threading
 import time
+from unittest import mock
 
-import mock
 import pytest
 
 from google.api_core import exceptions, retry
@@ -24,7 +24,7 @@
 
 
 class PollingFutureImpl(polling.PollingFuture):
-    def done(self):
+    def done(self, retry=None):
         return False
 
     def cancel(self):
@@ -33,9 +33,6 @@ def cancel(self):
     def cancelled(self):
         return False
 
-    def running(self):
-        return True
-
 
 def test_polling_future_constructor():
     future = PollingFutureImpl()
@@ -84,20 +81,23 @@ def test_invoke_callback_exception():
 
 
 class PollingFutureImplWithPoll(PollingFutureImpl):
-    def __init__(self):
+    def __init__(self, max_poll_count=1):
         super(PollingFutureImplWithPoll, self).__init__()
         self.poll_count = 0
         self.event = threading.Event()
+        self.max_poll_count = max_poll_count
 
-    def done(self, retry=polling.DEFAULT_RETRY):
+    def done(self, retry=None):
         self.poll_count += 1
+        if self.max_poll_count > self.poll_count:
+            return False
         self.event.wait()
         self.set_result(42)
         return True
 
 
-def test_result_with_polling():
-    future = PollingFutureImplWithPoll()
+def test_result_with_one_polling():
+    future = PollingFutureImplWithPoll(max_poll_count=1)
 
     future.event.set()
     result = future.result()
@@ -109,8 +109,34 @@ def test_result_with_polling():
     assert future.poll_count == 1
 
 
+def test_result_with_two_pollings():
+    future = PollingFutureImplWithPoll(max_poll_count=2)
+
+    future.event.set()
+    result = future.result()
+
+    assert result == 42
+    assert future.poll_count == 2
+    # Repeated calls should not cause additional polling
+    assert future.result() == result
+    assert future.poll_count == 2
+
+
+def test_result_with_two_pollings_custom_retry():
+    future = PollingFutureImplWithPoll(max_poll_count=2)
+
+    future.event.set()
+    result = future.result()
+
+    assert result == 42
+    assert future.poll_count == 2
+    # Repeated calls should not cause additional polling
+    assert future.result() == result
+    assert future.poll_count == 2
+
+
 class PollingFutureImplTimeout(PollingFutureImplWithPoll):
-    def done(self, retry=polling.DEFAULT_RETRY):
+    def done(self, retry=None):
         time.sleep(1)
         return False
 
@@ -132,11 +158,11 @@ def __init__(self, errors):
         super(PollingFutureImplTransient, self).__init__()
         self._errors = errors
 
-    def done(self, retry=polling.DEFAULT_RETRY):
+    def done(self, retry=None):
+        self.poll_count += 1
         if self._errors:
             error, self._errors = self._errors[0], self._errors[1:]
             raise error("testing")
-        self.poll_count += 1
         self.set_result(42)
         return True
 
@@ -144,17 +170,17 @@ def done(self, retry=polling.DEFAULT_RETRY):
 def test_result_transient_error():
     future = PollingFutureImplTransient(
         (
-            exceptions.TooManyRequests,
-            exceptions.InternalServerError,
-            exceptions.BadGateway,
+            polling._OperationNotComplete,
+            polling._OperationNotComplete,
+            polling._OperationNotComplete,
         )
     )
     result = future.result()
     assert result == 42
-    assert future.poll_count == 1
+    assert future.poll_count == 4
     # Repeated calls should not cause additional polling
     assert future.result() == result
-    assert future.poll_count == 1
+    assert future.poll_count == 4
 
 
 def test_callback_background_thread():
@@ -197,23 +223,23 @@ def test_double_callback_background_thread():
 
 
 class PollingFutureImplWithoutRetry(PollingFutureImpl):
-    def done(self):
+    def done(self, retry=None):
         return True
 
-    def result(self):
+    def result(self, timeout=None, retry=None, polling=None):
         return super(PollingFutureImplWithoutRetry, self).result()
 
-    def _blocking_poll(self, timeout):
+    def _blocking_poll(self, timeout=None, retry=None, polling=None):
         return super(PollingFutureImplWithoutRetry, self)._blocking_poll(
             timeout=timeout
         )
 
 
 class PollingFutureImplWith_done_or_raise(PollingFutureImpl):
-    def done(self):
+    def done(self, retry=None):
         return True
 
-    def _done_or_raise(self):
+    def _done_or_raise(self, retry=None):
         return super(PollingFutureImplWith_done_or_raise, self)._done_or_raise()
 
 
@@ -223,12 +249,12 @@ def test_polling_future_without_retry():
     )
     future = PollingFutureImplWithoutRetry()
     assert future.done()
-    assert future.running()
+    assert not future.running()
     assert future.result() is None
 
     with mock.patch.object(future, "done") as done_mock:
         future._done_or_raise()
-        done_mock.assert_called_once_with()
+        done_mock.assert_called_once_with(retry=None)
 
     with mock.patch.object(future, "done") as done_mock:
         future._done_or_raise(retry=custom_retry)
@@ -238,5 +264,5 @@ def test_polling_future_without_retry():
 def test_polling_future_with__done_or_raise():
     future = PollingFutureImplWith_done_or_raise()
     assert future.done()
-    assert future.running()
+    assert not future.running()
     assert future.result() is None
diff --git a/tests/unit/gapic/test_client_info.py b/tests/unit/gapic/test_client_info.py
index 64080ffd..2ca5c404 100644
--- a/tests/unit/gapic/test_client_info.py
+++ b/tests/unit/gapic/test_client_info.py
@@ -12,6 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import pytest
+
+try:
+    import grpc  # noqa: F401
+except ImportError:
+    pytest.skip("No GRPC", allow_module_level=True)
+
 
 from google.api_core.gapic_v1 import client_info
 
diff --git a/tests/unit/gapic/test_config.py b/tests/unit/gapic/test_config.py
index 1c15261d..5e42fde8 100644
--- a/tests/unit/gapic/test_config.py
+++ b/tests/unit/gapic/test_config.py
@@ -12,6 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import pytest
+
+try:
+    import grpc  # noqa: F401
+except ImportError:
+    pytest.skip("No GRPC", allow_module_level=True)
+
 from google.api_core import exceptions
 from google.api_core.gapic_v1 import config
 
diff --git a/tests/unit/gapic/test_method.py b/tests/unit/gapic/test_method.py
index e0ea57ac..87aa6390 100644
--- a/tests/unit/gapic/test_method.py
+++ b/tests/unit/gapic/test_method.py
@@ -13,8 +13,15 @@
 # limitations under the License.
 
 import datetime
+from unittest import mock
+
+import pytest
+
+try:
+    import grpc  # noqa: F401
+except ImportError:
+    pytest.skip("No GRPC", allow_module_level=True)
 
-import mock
 
 from google.api_core import exceptions
 from google.api_core import retry
@@ -32,27 +39,6 @@ def _utcnow_monotonic():
         curr_value += delta
 
 
-def test__determine_timeout():
-    # Check _determine_timeout always returns a Timeout object.
-    timeout_type_timeout = timeout.ConstantTimeout(600.0)
-    returned_timeout = google.api_core.gapic_v1.method._determine_timeout(
-        600.0, 600.0, None
-    )
-    assert isinstance(returned_timeout, timeout.ConstantTimeout)
-    returned_timeout = google.api_core.gapic_v1.method._determine_timeout(
-        600.0, timeout_type_timeout, None
-    )
-    assert isinstance(returned_timeout, timeout.ConstantTimeout)
-    returned_timeout = google.api_core.gapic_v1.method._determine_timeout(
-        timeout_type_timeout, 600.0, None
-    )
-    assert isinstance(returned_timeout, timeout.ConstantTimeout)
-    returned_timeout = google.api_core.gapic_v1.method._determine_timeout(
-        timeout_type_timeout, timeout_type_timeout, None
-    )
-    assert isinstance(returned_timeout, timeout.ConstantTimeout)
-
-
 def test_wrap_method_basic():
     method = mock.Mock(spec=["__call__"], return_value=42)
 
@@ -135,91 +121,71 @@ def test_invoke_wrapped_method_with_metadata_as_none():
 
 
 @mock.patch("time.sleep")
-def test_wrap_method_with_default_retry_and_timeout(unusued_sleep):
+def test_wrap_method_with_default_retry_and_timeout_and_compression(unused_sleep):
     method = mock.Mock(
         spec=["__call__"], side_effect=[exceptions.InternalServerError(None), 42]
     )
     default_retry = retry.Retry()
     default_timeout = timeout.ConstantTimeout(60)
+    default_compression = grpc.Compression.Gzip
     wrapped_method = google.api_core.gapic_v1.method.wrap_method(
-        method, default_retry, default_timeout
+        method, default_retry, default_timeout, default_compression
     )
 
     result = wrapped_method()
 
     assert result == 42
     assert method.call_count == 2
-    method.assert_called_with(timeout=60, metadata=mock.ANY)
+    method.assert_called_with(
+        timeout=60, compression=default_compression, metadata=mock.ANY
+    )
 
 
 @mock.patch("time.sleep")
-def test_wrap_method_with_default_retry_and_timeout_using_sentinel(unusued_sleep):
+def test_wrap_method_with_default_retry_and_timeout_using_sentinel(unused_sleep):
     method = mock.Mock(
         spec=["__call__"], side_effect=[exceptions.InternalServerError(None), 42]
     )
     default_retry = retry.Retry()
     default_timeout = timeout.ConstantTimeout(60)
+    default_compression = grpc.Compression.Gzip
     wrapped_method = google.api_core.gapic_v1.method.wrap_method(
-        method, default_retry, default_timeout
+        method, default_retry, default_timeout, default_compression
     )
 
     result = wrapped_method(
         retry=google.api_core.gapic_v1.method.DEFAULT,
         timeout=google.api_core.gapic_v1.method.DEFAULT,
+        compression=google.api_core.gapic_v1.method.DEFAULT,
     )
 
     assert result == 42
     assert method.call_count == 2
-    method.assert_called_with(timeout=60, metadata=mock.ANY)
+    method.assert_called_with(
+        timeout=60, compression=default_compression, metadata=mock.ANY
+    )
 
 
 @mock.patch("time.sleep")
-def test_wrap_method_with_overriding_retry_and_timeout(unusued_sleep):
+def test_wrap_method_with_overriding_retry_timeout_compression(unused_sleep):
     method = mock.Mock(spec=["__call__"], side_effect=[exceptions.NotFound(None), 42])
     default_retry = retry.Retry()
     default_timeout = timeout.ConstantTimeout(60)
+    default_compression = grpc.Compression.Gzip
     wrapped_method = google.api_core.gapic_v1.method.wrap_method(
-        method, default_retry, default_timeout
+        method, default_retry, default_timeout, default_compression
     )
 
     result = wrapped_method(
         retry=retry.Retry(retry.if_exception_type(exceptions.NotFound)),
         timeout=timeout.ConstantTimeout(22),
+        compression=grpc.Compression.Deflate,
     )
 
     assert result == 42
     assert method.call_count == 2
-    method.assert_called_with(timeout=22, metadata=mock.ANY)
-
-
-@mock.patch("time.sleep")
-@mock.patch(
-    "google.api_core.datetime_helpers.utcnow",
-    side_effect=_utcnow_monotonic(),
-    autospec=True,
-)
-def test_wrap_method_with_overriding_retry_deadline(utcnow, unused_sleep):
-    method = mock.Mock(
-        spec=["__call__"],
-        side_effect=([exceptions.InternalServerError(None)] * 4) + [42],
-    )
-    default_retry = retry.Retry()
-    default_timeout = timeout.ExponentialTimeout(deadline=60)
-    wrapped_method = google.api_core.gapic_v1.method.wrap_method(
-        method, default_retry, default_timeout
-    )
-
-    # Overriding only the retry's deadline should also override the timeout's
-    # deadline.
-    result = wrapped_method(retry=default_retry.with_deadline(30))
-
-    assert result == 42
-    timeout_args = [call[1]["timeout"] for call in method.call_args_list]
-    assert timeout_args == [5.0, 10.0, 20.0, 26.0, 25.0]
-    assert utcnow.call_count == (
-        1
-        + 5  # First to set the deadline.
-        + 5  # One for each min(timeout, maximum, (DEADLINE - NOW).seconds)
+    method.assert_called_with(
+        timeout=22, compression=grpc.Compression.Deflate, metadata=mock.ANY
     )
 
 
@@ -235,3 +201,24 @@ def test_wrap_method_with_overriding_timeout_as_a_number():
 
     assert result == 42
     method.assert_called_once_with(timeout=22, metadata=mock.ANY)
+
+
+def test_wrap_method_with_call():
+    method = mock.Mock()
+    mock_call = mock.Mock()
+    method.with_call.return_value = 42, mock_call
+
+    wrapped_method = google.api_core.gapic_v1.method.wrap_method(method, with_call=True)
+    result = wrapped_method()
+    assert len(result) == 2
+    assert result[0] == 42
+    assert result[1] == mock_call
+
+
+def test_wrap_method_with_call_not_supported():
+    """Raises an error if wrapped callable doesn't have with_call method."""
+    method = lambda: None  # noqa: E731
+
+    with pytest.raises(ValueError) as exc_info:
+        google.api_core.gapic_v1.method.wrap_method(method, with_call=True)
+    assert "with_call=True is only supported for unary calls" in str(exc_info.value)
diff --git a/tests/unit/gapic/test_routing_header.py b/tests/unit/gapic/test_routing_header.py
index 77300e87..2c8c7546 100644
--- a/tests/unit/gapic/test_routing_header.py
+++ b/tests/unit/gapic/test_routing_header.py
@@ -12,6 +12,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from enum import Enum
+
+import pytest
+
+try:
+    import grpc  # noqa: F401
+except ImportError:
+    pytest.skip("No GRPC", allow_module_level=True)
+
 
 from google.api_core.gapic_v1 import routing_header
 
@@ -28,7 +37,67 @@ def test_to_routing_header_with_slashes():
     assert value == "name=me/ep&book.read=1%262"
 
 
+def test_enum_fully_qualified():
+    class Message:
+        class Color(Enum):
+            RED = 1
+            GREEN = 2
+            BLUE = 3
+
+    params = [("color", Message.Color.RED)]
+    value = routing_header.to_routing_header(params)
+    assert value == "color=Color.RED"
+    value = routing_header.to_routing_header(params, qualified_enums=True)
+    assert value == "color=Color.RED"
+
+
+def test_enum_nonqualified():
+    class Message:
+        class Color(Enum):
+            RED = 1
+            GREEN = 2
+            BLUE = 3
+
+    params = [("color", Message.Color.RED), ("num", 5)]
+    value = routing_header.to_routing_header(params, qualified_enums=False)
+    assert value == "color=RED&num=5"
+    params = {"color": Message.Color.RED, "num": 5}
+    value = routing_header.to_routing_header(params, qualified_enums=False)
+    assert value == "color=RED&num=5"
+
+
 def test_to_grpc_metadata():
     params = [("name", "meep"), ("book.read", "1")]
     metadata = routing_header.to_grpc_metadata(params)
     assert metadata == (routing_header.ROUTING_METADATA_KEY, "name=meep&book.read=1")
+
+
+@pytest.mark.parametrize(
+    "key,value,expected",
+    [
+        ("book.read", "1", "book.read=1"),
+        ("name", "me/ep", "name=me/ep"),
+        ("\\", "=", "%5C=%3D"),
+        (b"hello", "world", "hello=world"),
+        ("✔️", "✌️", "%E2%9C%94%EF%B8%8F=%E2%9C%8C%EF%B8%8F"),
+    ],
+)
+def test__urlencode_param(key, value, expected):
+    result = routing_header._urlencode_param(key, value)
+    assert result == expected
+
+
+def test__urlencode_param_caching_performance():
+    import time
+
+    key = "key" * 100
+    value = "value" * 100
+    # time with empty cache
+    start_time = time.perf_counter()
+    routing_header._urlencode_param(key, value)
+    duration = time.perf_counter() - start_time
+    second_start_time = time.perf_counter()
+    routing_header._urlencode_param(key, value)
+    second_duration = time.perf_counter() - second_start_time
+    # second call should be approximately 10 times faster
+    assert second_duration < duration / 10
diff --git a/tests/unit/operations_v1/test_operations_client.py b/tests/unit/operations_v1/test_operations_client.py
index 001b8fea..fb4b14f1 100644
--- a/tests/unit/operations_v1/test_operations_client.py
+++ b/tests/unit/operations_v1/test_operations_client.py
@@ -12,9 +12,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import pytest
+
+try:
+    import grpc  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    pytest.skip("No GRPC", allow_module_level=True)
+
 from google.api_core import grpc_helpers
 from google.api_core import operations_v1
 from google.api_core import page_iterator
+from google.api_core.operations_v1 import operations_client_config
 from google.longrunning import operations_pb2
 from google.protobuf import empty_pb2
 
@@ -89,3 +97,7 @@ def test_cancel_operation():
     ].metadata
     assert len(channel.CancelOperation.requests) == 1
     assert channel.CancelOperation.requests[0].name == "name"
+
+
+def test_operations_client_config():
+    assert operations_client_config.config["interfaces"]
diff --git a/tests/unit/operations_v1/test_operations_rest_client.py b/tests/unit/operations_v1/test_operations_rest_client.py
new file mode 100644
index 00000000..d1f6e0eb
--- /dev/null
+++ b/tests/unit/operations_v1/test_operations_rest_client.py
@@ -0,0 +1,1401 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+import os
+
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock  # pragma: NO COVER  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    import mock  # type: ignore
+
+import pytest
+from typing import Any, List
+
+try:
+    import grpc  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    pytest.skip("No GRPC", allow_module_level=True)
+from requests import Response  # noqa I201
+from google.auth.transport.requests import AuthorizedSession
+
+from google.api_core import client_options
+from google.api_core import exceptions as core_exceptions
+from google.api_core import gapic_v1
+from google.api_core.operations_v1 import AbstractOperationsClient
+
+import google.auth
+from google.api_core.operations_v1 import pagers
+from google.api_core.operations_v1 import pagers_async
+from google.api_core.operations_v1 import transports
+from google.auth import credentials as ga_credentials
+from google.auth.exceptions import MutualTLSChannelError
+from google.longrunning import operations_pb2
+from google.oauth2 import service_account
+from google.protobuf import json_format  # type: ignore
+from google.rpc import status_pb2  # type: ignore
+
+try:
+    import aiohttp  # noqa: F401
+    import google.auth.aio.transport
+    from google.auth.aio.transport.sessions import AsyncAuthorizedSession
+    from google.api_core.operations_v1 import AsyncOperationsRestClient
+    from google.auth.aio import credentials as ga_credentials_async
+
+    GOOGLE_AUTH_AIO_INSTALLED = True
+except ImportError:
+    GOOGLE_AUTH_AIO_INSTALLED = False
+
+HTTP_OPTIONS = {
+    "google.longrunning.Operations.CancelOperation": [
+        {"method": "post", "uri": "/v3/{name=operations/*}:cancel", "body": "*"},
+    ],
+    "google.longrunning.Operations.DeleteOperation": [
+        {"method": "delete", "uri": "/v3/{name=operations/*}"},
+    ],
+    "google.longrunning.Operations.GetOperation": [
+        {"method": "get", "uri": "/v3/{name=operations/*}"},
+    ],
+    "google.longrunning.Operations.ListOperations": [
+        {"method": "get", "uri": "/v3/{name=operations}"},
+    ],
+}
+
+PYPARAM_CLIENT: List[Any] = [
+    AbstractOperationsClient,
+]
+PYPARAM_CLIENT_TRANSPORT_NAME = [
+    [AbstractOperationsClient, transports.OperationsRestTransport, "rest"],
+]
+PYPARAM_CLIENT_TRANSPORT_CREDENTIALS = [
+    [
+        AbstractOperationsClient,
+        transports.OperationsRestTransport,
+        ga_credentials.AnonymousCredentials(),
+    ],
+]
+
+if GOOGLE_AUTH_AIO_INSTALLED:
+    PYPARAM_CLIENT.append(AsyncOperationsRestClient)
+    PYPARAM_CLIENT_TRANSPORT_NAME.append(
+        [
+            AsyncOperationsRestClient,
+            transports.AsyncOperationsRestTransport,
+            "rest_asyncio",
+        ]
+    )
+    PYPARAM_CLIENT_TRANSPORT_CREDENTIALS.append(
+        [
+            AsyncOperationsRestClient,
+            transports.AsyncOperationsRestTransport,
+            ga_credentials_async.AnonymousCredentials(),
+        ]
+    )
+
+
+def client_cert_source_callback():
+    return b"cert bytes", b"key bytes"
+
+
+def _get_session_type(is_async: bool):
+    return (
+        AsyncAuthorizedSession
+        if is_async and GOOGLE_AUTH_AIO_INSTALLED
+        else AuthorizedSession
+    )
+
+
+def _get_operations_client(is_async: bool, http_options=HTTP_OPTIONS):
+    if is_async and GOOGLE_AUTH_AIO_INSTALLED:
+        async_transport = transports.rest_asyncio.AsyncOperationsRestTransport(
+            credentials=ga_credentials_async.AnonymousCredentials(),
+            http_options=http_options,
+        )
+        return AsyncOperationsRestClient(transport=async_transport)
+    else:
+        sync_transport = transports.rest.OperationsRestTransport(
+            credentials=ga_credentials.AnonymousCredentials(), http_options=http_options
+        )
+        return AbstractOperationsClient(transport=sync_transport)
+
+
+# If default endpoint is localhost, then default mtls endpoint will be the same.
+# This method modifies the default endpoint so the client can produce a different
+# mtls endpoint for endpoint testing purposes.
+def modify_default_endpoint(client):
+    return (
+        "foo.googleapis.com"
+        if ("localhost" in client.DEFAULT_ENDPOINT)
+        else client.DEFAULT_ENDPOINT
+    )
+
+
+# TODO: Add support for mtls in async rest
+@pytest.mark.parametrize(
+    "client_class",
+    [
+        AbstractOperationsClient,
+    ],
+)
+def test__get_default_mtls_endpoint(client_class):
+    api_endpoint = "example.googleapis.com"
+    api_mtls_endpoint = "example.mtls.googleapis.com"
+    sandbox_endpoint = "example.sandbox.googleapis.com"
+    sandbox_mtls_endpoint = "example.mtls.sandbox.googleapis.com"
+    non_googleapi = "api.example.com"
+
+    assert client_class._get_default_mtls_endpoint(None) is None
+    assert client_class._get_default_mtls_endpoint(api_endpoint) == api_mtls_endpoint
+    assert (
+        client_class._get_default_mtls_endpoint(api_mtls_endpoint) == api_mtls_endpoint
+    )
+    assert (
+        client_class._get_default_mtls_endpoint(sandbox_endpoint)
+        == sandbox_mtls_endpoint
+    )
+    assert (
+        client_class._get_default_mtls_endpoint(sandbox_mtls_endpoint)
+        == sandbox_mtls_endpoint
+    )
+    assert client_class._get_default_mtls_endpoint(non_googleapi) == non_googleapi
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_operations_client_from_service_account_info(client_class):
+    creds = ga_credentials.AnonymousCredentials()
+    if "async" in str(client_class):
+        # TODO(): Add support for service account info to async REST transport.
+        with pytest.raises(NotImplementedError):
+            info = {"valid": True}
+            client_class.from_service_account_info(info)
+    else:
+        with mock.patch.object(
+            service_account.Credentials, "from_service_account_info"
+        ) as factory:
+            factory.return_value = creds
+            info = {"valid": True}
+            client = client_class.from_service_account_info(info)
+            assert client.transport._credentials == creds
+            assert isinstance(client, client_class)
+
+            assert client.transport._host == "https://longrunning.googleapis.com"
+
+
+@pytest.mark.parametrize(
+    "transport_class",
+    [
+        transports.OperationsRestTransport,
+        # TODO(https://github.com/googleapis/python-api-core/issues/706): Add support for
+        # service account credentials in transports.AsyncOperationsRestTransport
+    ],
+)
+def test_operations_client_service_account_always_use_jwt(transport_class):
+    with mock.patch.object(
+        service_account.Credentials, "with_always_use_jwt_access", create=True
+    ) as use_jwt:
+        creds = service_account.Credentials(None, None, None)
+        transport_class(credentials=creds, always_use_jwt_access=True)
+        use_jwt.assert_called_once_with(True)
+
+    with mock.patch.object(
+        service_account.Credentials, "with_always_use_jwt_access", create=True
+    ) as use_jwt:
+        creds = service_account.Credentials(None, None, None)
+        transport_class(credentials=creds, always_use_jwt_access=False)
+        use_jwt.assert_not_called()
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_operations_client_from_service_account_file(client_class):
+
+    if "async" in str(client_class):
+        # TODO(): Add support for service account creds to async REST transport.
+        with pytest.raises(NotImplementedError):
+            client_class.from_service_account_file("dummy/file/path.json")
+    else:
+        creds = ga_credentials.AnonymousCredentials()
+        with mock.patch.object(
+            service_account.Credentials, "from_service_account_file"
+        ) as factory:
+            factory.return_value = creds
+            client = client_class.from_service_account_file("dummy/file/path.json")
+            assert client.transport._credentials == creds
+            assert isinstance(client, client_class)
+
+            client = client_class.from_service_account_json("dummy/file/path.json")
+            assert client.transport._credentials == creds
+            assert isinstance(client, client_class)
+
+            assert client.transport._host == "https://longrunning.googleapis.com"
+
+
+@pytest.mark.parametrize(
+    "client_class,transport_class,transport_name",
+    PYPARAM_CLIENT_TRANSPORT_NAME,
+)
+def test_operations_client_get_transport_class(
+    client_class, transport_class, transport_name
+):
+    transport = client_class.get_transport_class()
+    available_transports = [
+        transports.OperationsRestTransport,
+    ]
+    if GOOGLE_AUTH_AIO_INSTALLED:
+        available_transports.append(transports.AsyncOperationsRestTransport)
+    assert transport in available_transports
+
+    transport = client_class.get_transport_class(transport_name)
+    assert transport == transport_class
+
+
+# TODO(): Update this test case to include async REST once we have support for MTLS.
+@pytest.mark.parametrize(
+    "client_class,transport_class,transport_name",
+    [(AbstractOperationsClient, transports.OperationsRestTransport, "rest")],
+)
+@mock.patch.object(
+    AbstractOperationsClient,
+    "DEFAULT_ENDPOINT",
+    modify_default_endpoint(AbstractOperationsClient),
+)
+def test_operations_client_client_options(
+    client_class, transport_class, transport_name
+):
+    # # Check that if channel is provided we won't create a new one.
+    # with mock.patch.object(AbstractOperationsBaseClient, "get_transport_class") as gtc:
+    #     client = client_class(transport=transport_class())
+    #     gtc.assert_not_called()
+
+    # # Check that if channel is provided via str we will create a new one.
+    # with mock.patch.object(AbstractOperationsBaseClient, "get_transport_class") as gtc:
+    #     client = client_class(transport=transport_name)
+    #     gtc.assert_called()
+
+    # Check the case api_endpoint is provided.
+    options = client_options.ClientOptions(api_endpoint="squid.clam.whelk")
+    with mock.patch.object(transport_class, "__init__") as patched:
+        patched.return_value = None
+        client = client_class(client_options=options, transport=transport_name)
+        patched.assert_called_once_with(
+            credentials=None,
+            credentials_file=None,
+            host="squid.clam.whelk",
+            scopes=None,
+            client_cert_source_for_mtls=None,
+            quota_project_id=None,
+            client_info=transports.base.DEFAULT_CLIENT_INFO,
+            always_use_jwt_access=True,
+        )
+
+    # Check the case api_endpoint is not provided and GOOGLE_API_USE_MTLS_ENDPOINT is
+    # "never".
+    with mock.patch.dict(os.environ, {"GOOGLE_API_USE_MTLS_ENDPOINT": "never"}):
+        with mock.patch.object(transport_class, "__init__") as patched:
+            patched.return_value = None
+            client = client_class(transport=transport_name)
+            patched.assert_called_once_with(
+                credentials=None,
+                credentials_file=None,
+                host=client.DEFAULT_ENDPOINT,
+                scopes=None,
+                client_cert_source_for_mtls=None,
+                quota_project_id=None,
+                client_info=transports.base.DEFAULT_CLIENT_INFO,
+                always_use_jwt_access=True,
+            )
+
+    # Check the case api_endpoint is not provided and GOOGLE_API_USE_MTLS_ENDPOINT is
+    # "always".
+    with mock.patch.dict(os.environ, {"GOOGLE_API_USE_MTLS_ENDPOINT": "always"}):
+        with mock.patch.object(transport_class, "__init__") as patched:
+            patched.return_value = None
+            client = client_class(transport=transport_name)
+            patched.assert_called_once_with(
+                credentials=None,
+                credentials_file=None,
+                host=client.DEFAULT_MTLS_ENDPOINT,
+                scopes=None,
+                client_cert_source_for_mtls=None,
+                quota_project_id=None,
+                client_info=transports.base.DEFAULT_CLIENT_INFO,
+                always_use_jwt_access=True,
+            )
+
+    # Check the case api_endpoint is not provided and GOOGLE_API_USE_MTLS_ENDPOINT has
+    # unsupported value.
+    with mock.patch.dict(os.environ, {"GOOGLE_API_USE_MTLS_ENDPOINT": "Unsupported"}):
+        with pytest.raises(MutualTLSChannelError):
+            client = client_class()
+
+    # Check the case GOOGLE_API_USE_CLIENT_CERTIFICATE has unsupported value.
+    with mock.patch.dict(
+        os.environ, {"GOOGLE_API_USE_CLIENT_CERTIFICATE": "Unsupported"}
+    ):
+        with pytest.raises(ValueError):
+            client = client_class()
+
+    # Check the case quota_project_id is provided
+    options = client_options.ClientOptions(quota_project_id="octopus")
+    with mock.patch.object(transport_class, "__init__") as patched:
+        patched.return_value = None
+        client = client_class(client_options=options, transport=transport_name)
+        patched.assert_called_once_with(
+            credentials=None,
+            credentials_file=None,
+            host=client.DEFAULT_ENDPOINT,
+            scopes=None,
+            client_cert_source_for_mtls=None,
+            quota_project_id="octopus",
+            client_info=transports.base.DEFAULT_CLIENT_INFO,
+            always_use_jwt_access=True,
+        )
+
+
+# TODO: Add support for mtls in async REST
+@pytest.mark.parametrize(
+    "client_class,transport_class,transport_name,use_client_cert_env",
+    [
+        (AbstractOperationsClient, transports.OperationsRestTransport, "rest", "true"),
+        (AbstractOperationsClient, transports.OperationsRestTransport, "rest", "false"),
+    ],
+)
+@mock.patch.object(
+    AbstractOperationsClient,
+    "DEFAULT_ENDPOINT",
+    modify_default_endpoint(AbstractOperationsClient),
+)
+@mock.patch.dict(os.environ, {"GOOGLE_API_USE_MTLS_ENDPOINT": "auto"})
+def test_operations_client_mtls_env_auto(
+    client_class, transport_class, transport_name, use_client_cert_env
+):
+    # This tests the endpoint autoswitch behavior. Endpoint is autoswitched to the default
+    # mtls endpoint, if GOOGLE_API_USE_CLIENT_CERTIFICATE is "true" and client cert exists.
+
+    # Check the case client_cert_source is provided. Whether client cert is used depends on
+    # GOOGLE_API_USE_CLIENT_CERTIFICATE value.
+    with mock.patch.dict(
+        os.environ, {"GOOGLE_API_USE_CLIENT_CERTIFICATE": use_client_cert_env}
+    ):
+        options = client_options.ClientOptions(
+            client_cert_source=client_cert_source_callback
+        )
+
+        def fake_init(client_cert_source_for_mtls=None, **kwargs):
+            """Invoke client_cert source if provided."""
+
+            if client_cert_source_for_mtls:
+                client_cert_source_for_mtls()
+                return None
+
+        with mock.patch.object(transport_class, "__init__") as patched:
+            patched.side_effect = fake_init
+            client = client_class(client_options=options)
+
+            if use_client_cert_env == "false":
+                expected_client_cert_source = None
+                expected_host = client.DEFAULT_ENDPOINT
+            else:
+                expected_client_cert_source = client_cert_source_callback
+                expected_host = client.DEFAULT_MTLS_ENDPOINT
+
+            patched.assert_called_once_with(
+                credentials=None,
+                credentials_file=None,
+                host=expected_host,
+                scopes=None,
+                client_cert_source_for_mtls=expected_client_cert_source,
+                quota_project_id=None,
+                client_info=transports.base.DEFAULT_CLIENT_INFO,
+                always_use_jwt_access=True,
+            )
+
+    # Check the case ADC client cert is provided. Whether client cert is used depends on
+    # GOOGLE_API_USE_CLIENT_CERTIFICATE value.
+    with mock.patch.dict(
+        os.environ, {"GOOGLE_API_USE_CLIENT_CERTIFICATE": use_client_cert_env}
+    ):
+        with mock.patch.object(transport_class, "__init__") as patched:
+            with mock.patch(
+                "google.auth.transport.mtls.has_default_client_cert_source",
+                return_value=True,
+            ):
+                with mock.patch(
+                    "google.auth.transport.mtls.default_client_cert_source",
+                    return_value=client_cert_source_callback,
+                ):
+                    if use_client_cert_env == "false":
+                        expected_host = client.DEFAULT_ENDPOINT
+                        expected_client_cert_source = None
+                    else:
+                        expected_host = client.DEFAULT_MTLS_ENDPOINT
+                        expected_client_cert_source = client_cert_source_callback
+
+                    patched.return_value = None
+                    client = client_class()
+                    patched.assert_called_once_with(
+                        credentials=None,
+                        credentials_file=None,
+                        host=expected_host,
+                        scopes=None,
+                        client_cert_source_for_mtls=expected_client_cert_source,
+                        quota_project_id=None,
+                        client_info=transports.base.DEFAULT_CLIENT_INFO,
+                        always_use_jwt_access=True,
+                    )
+
+    # Check the case client_cert_source and ADC client cert are not provided.
+    with mock.patch.dict(
+        os.environ, {"GOOGLE_API_USE_CLIENT_CERTIFICATE": use_client_cert_env}
+    ):
+        with mock.patch.object(transport_class, "__init__") as patched:
+            with mock.patch(
+                "google.auth.transport.mtls.has_default_client_cert_source",
+                return_value=False,
+            ):
+                patched.return_value = None
+                client = client_class()
+                patched.assert_called_once_with(
+                    credentials=None,
+                    credentials_file=None,
+                    host=client.DEFAULT_ENDPOINT,
+                    scopes=None,
+                    client_cert_source_for_mtls=None,
+                    quota_project_id=None,
+                    client_info=transports.base.DEFAULT_CLIENT_INFO,
+                    always_use_jwt_access=True,
+                )
+
+
+@pytest.mark.parametrize(
+    "client_class,transport_class,transport_name",
+    PYPARAM_CLIENT_TRANSPORT_NAME,
+)
+def test_operations_client_client_options_scopes(
+    client_class, transport_class, transport_name
+):
+    # Check the case scopes are provided.
+    options = client_options.ClientOptions(
+        scopes=["1", "2"],
+    )
+    if "async" in str(client_class):
+        # TODO(): Add support for scopes to async REST transport.
+        with pytest.raises(core_exceptions.AsyncRestUnsupportedParameterError):
+            client_class(client_options=options, transport=transport_name)
+    else:
+        with mock.patch.object(transport_class, "__init__") as patched:
+            patched.return_value = None
+            client = client_class(client_options=options, transport=transport_name)
+            patched.assert_called_once_with(
+                credentials=None,
+                credentials_file=None,
+                host=client.DEFAULT_ENDPOINT,
+                scopes=["1", "2"],
+                client_cert_source_for_mtls=None,
+                quota_project_id=None,
+                client_info=transports.base.DEFAULT_CLIENT_INFO,
+                always_use_jwt_access=True,
+            )
+
+
+@pytest.mark.parametrize(
+    "client_class,transport_class,transport_name",
+    PYPARAM_CLIENT_TRANSPORT_NAME,
+)
+def test_operations_client_client_options_credentials_file(
+    client_class, transport_class, transport_name
+):
+    # Check the case credentials file is provided.
+    options = client_options.ClientOptions(credentials_file="credentials.json")
+    if "async" in str(client_class):
+        # TODO(): Add support for credentials file to async REST transport.
+        with pytest.raises(core_exceptions.AsyncRestUnsupportedParameterError):
+            client_class(client_options=options, transport=transport_name)
+    else:
+        with mock.patch.object(transport_class, "__init__") as patched:
+            patched.return_value = None
+            client = client_class(client_options=options, transport=transport_name)
+            patched.assert_called_once_with(
+                credentials=None,
+                credentials_file="credentials.json",
+                host=client.DEFAULT_ENDPOINT,
+                scopes=None,
+                client_cert_source_for_mtls=None,
+                quota_project_id=None,
+                client_info=transports.base.DEFAULT_CLIENT_INFO,
+                always_use_jwt_access=True,
+            )
+
+
+def test_list_operations_rest():
+    client = _get_operations_client(is_async=False)
+    # Mock the http request call within the method and fake a response.
+    with mock.patch.object(_get_session_type(is_async=False), "request") as req:
+        # Designate an appropriate value for the returned response.
+        return_value = operations_pb2.ListOperationsResponse(
+            next_page_token="next_page_token_value",
+        )
+
+        # Wrap the value into a proper Response obj
+        response_value = Response()
+        response_value.status_code = 200
+        json_return_value = json_format.MessageToJson(return_value)
+        response_value._content = json_return_value.encode("UTF-8")
+        req.return_value = response_value
+        response = client.list_operations(
+            name="operations", filter_="my_filter", page_size=10, page_token="abc"
+        )
+
+        actual_args = req.call_args
+        assert actual_args.args[0] == "GET"
+        assert actual_args.args[1] == "https://longrunning.googleapis.com/v3/operations"
+        assert actual_args.kwargs["params"] == [
+            ("filter", "my_filter"),
+            ("pageSize", 10),
+            ("pageToken", "abc"),
+        ]
+
+    # Establish that the response is the type that we expect.
+    assert isinstance(response, pagers.ListOperationsPager)
+    assert response.next_page_token == "next_page_token_value"
+
+
+@pytest.mark.asyncio
+async def test_list_operations_rest_async():
+    if not GOOGLE_AUTH_AIO_INSTALLED:
+        pytest.skip("Skipped because google-api-core[async_rest] is not installed")
+
+    client = _get_operations_client(is_async=True)
+    # Mock the http request call within the method and fake a response.
+    with mock.patch.object(_get_session_type(is_async=True), "request") as req:
+        # Designate an appropriate value for the returned response.
+        return_value = operations_pb2.ListOperationsResponse(
+            next_page_token="next_page_token_value",
+        )
+
+        # Wrap the value into a proper Response obj
+        response_value = mock.Mock()
+        response_value.status_code = 200
+        json_return_value = json_format.MessageToJson(return_value)
+        response_value.read = mock.AsyncMock(
+            return_value=json_return_value.encode("UTF-8")
+        )
+        req.return_value = response_value
+        response = await client.list_operations(
+            name="operations", filter_="my_filter", page_size=10, page_token="abc"
+        )
+
+        actual_args = req.call_args
+        assert actual_args.args[0] == "GET"
+        assert actual_args.args[1] == "https://longrunning.googleapis.com/v3/operations"
+        assert actual_args.kwargs["params"] == [
+            ("filter", "my_filter"),
+            ("pageSize", 10),
+            ("pageToken", "abc"),
+        ]
+
+    # Establish that the response is the type that we expect.
+    assert isinstance(response, pagers_async.ListOperationsAsyncPager)
+    assert response.next_page_token == "next_page_token_value"
+
+
+def test_list_operations_rest_failure():
+    client = _get_operations_client(is_async=False, http_options=None)
+
+    with mock.patch.object(_get_session_type(is_async=False), "request") as req:
+        response_value = Response()
+        response_value.status_code = 400
+        mock_request = mock.MagicMock()
+        mock_request.method = "GET"
+        mock_request.url = "https://longrunning.googleapis.com:443/v1/operations"
+        response_value.request = mock_request
+        req.return_value = response_value
+        with pytest.raises(core_exceptions.GoogleAPIError):
+            client.list_operations(name="operations")
+
+
+@pytest.mark.asyncio
+async def test_list_operations_rest_failure_async():
+    if not GOOGLE_AUTH_AIO_INSTALLED:
+        pytest.skip("Skipped because google-api-core[async_rest] is not installed")
+
+    client = _get_operations_client(is_async=True, http_options=None)
+
+    with mock.patch.object(_get_session_type(is_async=True), "request") as req:
+        response_value = mock.Mock()
+        response_value.status_code = 400
+        response_value.read = mock.AsyncMock(return_value=b"{}")
+        mock_request = mock.MagicMock()
+        mock_request.method = "GET"
+        mock_request.url = "https://longrunning.googleapis.com:443/v1/operations"
+        response_value.request = mock_request
+        req.return_value = response_value
+        with pytest.raises(core_exceptions.GoogleAPIError):
+            await client.list_operations(name="operations")
+
+
+def test_list_operations_rest_pager():
+    client = _get_operations_client(is_async=False, http_options=None)
+
+    # Mock the http request call within the method and fake a response.
+    with mock.patch.object(_get_session_type(is_async=False), "request") as req:
+        # TODO(kbandes): remove this mock unless there's a good reason for it.
+        # with mock.patch.object(path_template, 'transcode') as transcode:
+        # Set the response as a series of pages
+        response = (
+            operations_pb2.ListOperationsResponse(
+                operations=[
+                    operations_pb2.Operation(),
+                    operations_pb2.Operation(),
+                    operations_pb2.Operation(),
+                ],
+                next_page_token="abc",
+            ),
+            operations_pb2.ListOperationsResponse(
+                operations=[],
+                next_page_token="def",
+            ),
+            operations_pb2.ListOperationsResponse(
+                operations=[operations_pb2.Operation()],
+                next_page_token="ghi",
+            ),
+            operations_pb2.ListOperationsResponse(
+                operations=[operations_pb2.Operation(), operations_pb2.Operation()],
+            ),
+        )
+        # Two responses for two calls
+        response = response + response
+
+        # Wrap the values into proper Response objs
+        response = tuple(json_format.MessageToJson(x) for x in response)
+        return_values = tuple(Response() for i in response)
+        for return_val, response_val in zip(return_values, response):
+            return_val._content = response_val.encode("UTF-8")
+            return_val.status_code = 200
+        req.side_effect = return_values
+
+        pager = client.list_operations(name="operations")
+
+        results = list(pager)
+        assert len(results) == 6
+        assert all(isinstance(i, operations_pb2.Operation) for i in results)
+
+        pages = list(client.list_operations(name="operations").pages)
+        for page_, token in zip(pages, ["abc", "def", "ghi", ""]):
+            assert page_.next_page_token == token
+
+
+@pytest.mark.asyncio
+async def test_list_operations_rest_pager_async():
+    if not GOOGLE_AUTH_AIO_INSTALLED:
+        pytest.skip("Skipped because google-api-core[async_rest] is not installed")
+    client = _get_operations_client(is_async=True, http_options=None)
+
+    # Mock the http request call within the method and fake a response.
+    with mock.patch.object(_get_session_type(is_async=True), "request") as req:
+        # TODO(kbandes): remove this mock unless there's a good reason for it.
+        # with mock.patch.object(path_template, 'transcode') as transcode:
+        # Set the response as a series of pages
+        response = (
+            operations_pb2.ListOperationsResponse(
+                operations=[
+                    operations_pb2.Operation(),
+                    operations_pb2.Operation(),
+                    operations_pb2.Operation(),
+                ],
+                next_page_token="abc",
+            ),
+            operations_pb2.ListOperationsResponse(
+                operations=[],
+                next_page_token="def",
+            ),
+            operations_pb2.ListOperationsResponse(
+                operations=[operations_pb2.Operation()],
+                next_page_token="ghi",
+            ),
+            operations_pb2.ListOperationsResponse(
+                operations=[operations_pb2.Operation(), operations_pb2.Operation()],
+            ),
+        )
+        # Two responses for two calls
+        response = response + response
+
+        # Wrap the values into proper Response objs
+        response = tuple(json_format.MessageToJson(x) for x in response)
+        return_values = tuple(mock.Mock() for i in response)
+        for return_val, response_val in zip(return_values, response):
+            return_val.read = mock.AsyncMock(return_value=response_val.encode("UTF-8"))
+            return_val.status_code = 200
+        req.side_effect = return_values
+
+        pager = await client.list_operations(name="operations")
+
+        responses = []
+        async for response in pager:
+            responses.append(response)
+
+        results = list(responses)
+        assert len(results) == 6
+        assert all(isinstance(i, operations_pb2.Operation) for i in results)
+        pager = await client.list_operations(name="operations")
+
+        responses = []
+        async for response in pager:
+            responses.append(response)
+
+        assert len(responses) == 6
+        assert all(isinstance(i, operations_pb2.Operation) for i in results)
+
+        pages = []
+
+        async for page in pager.pages:
+            pages.append(page)
+        for page_, token in zip(pages, ["", "", "", "abc", "def", "ghi", ""]):
+            assert page_.next_page_token == token
+
+
+def test_get_operation_rest():
+    client = _get_operations_client(is_async=False)
+
+    # Mock the http request call within the method and fake a response.
+    with mock.patch.object(_get_session_type(is_async=False), "request") as req:
+        # Designate an appropriate value for the returned response.
+        return_value = operations_pb2.Operation(
+            name="operations/sample1",
+            done=True,
+            error=status_pb2.Status(code=411),
+        )
+
+        # Wrap the value into a proper Response obj
+        response_value = Response()
+        response_value.status_code = 200
+        json_return_value = json_format.MessageToJson(return_value)
+        response_value._content = json_return_value.encode("UTF-8")
+        req.return_value = response_value
+        response = client.get_operation("operations/sample1")
+
+    actual_args = req.call_args
+    assert actual_args.args[0] == "GET"
+    assert (
+        actual_args.args[1]
+        == "https://longrunning.googleapis.com/v3/operations/sample1"
+    )
+
+    # Establish that the response is the type that we expect.
+    assert isinstance(response, operations_pb2.Operation)
+    assert response.name == "operations/sample1"
+    assert response.done is True
+
+
+@pytest.mark.asyncio
+async def test_get_operation_rest_async():
+    if not GOOGLE_AUTH_AIO_INSTALLED:
+        pytest.skip("Skipped because google-api-core[async_rest] is not installed")
+    client = _get_operations_client(is_async=True)
+
+    # Mock the http request call within the method and fake a response.
+    with mock.patch.object(_get_session_type(is_async=True), "request") as req:
+        # Designate an appropriate value for the returned response.
+        return_value = operations_pb2.Operation(
+            name="operations/sample1",
+            done=True,
+            error=status_pb2.Status(code=411),
+        )
+
+        # Wrap the value into a proper Response obj
+        response_value = mock.Mock()
+        response_value.status_code = 200
+        json_return_value = json_format.MessageToJson(return_value)
+        response_value.read = mock.AsyncMock(return_value=json_return_value)
+        req.return_value = response_value
+        response = await client.get_operation("operations/sample1")
+
+    actual_args = req.call_args
+    assert actual_args.args[0] == "GET"
+    assert (
+        actual_args.args[1]
+        == "https://longrunning.googleapis.com/v3/operations/sample1"
+    )
+
+    # Establish that the response is the type that we expect.
+    assert isinstance(response, operations_pb2.Operation)
+    assert response.name == "operations/sample1"
+    assert response.done is True
+
+
+def test_get_operation_rest_failure():
+    client = _get_operations_client(is_async=False, http_options=None)
+
+    with mock.patch.object(_get_session_type(is_async=False), "request") as req:
+        response_value = Response()
+        response_value.status_code = 400
+        mock_request = mock.MagicMock()
+        mock_request.method = "GET"
+        mock_request.url = "https://longrunning.googleapis.com/v1/operations/sample1"
+        response_value.request = mock_request
+        req.return_value = response_value
+        with pytest.raises(core_exceptions.GoogleAPIError):
+            client.get_operation("sample0/operations/sample1")
+
+
+@pytest.mark.asyncio
+async def test_get_operation_rest_failure_async():
+    if not GOOGLE_AUTH_AIO_INSTALLED:
+        pytest.skip("Skipped because google-api-core[async_rest] is not installed")
+    client = _get_operations_client(is_async=True, http_options=None)
+
+    with mock.patch.object(_get_session_type(is_async=True), "request") as req:
+        response_value = mock.Mock()
+        response_value.status_code = 400
+        response_value.read = mock.AsyncMock(return_value=b"{}")
+        mock_request = mock.MagicMock()
+        mock_request.method = "GET"
+        mock_request.url = "https://longrunning.googleapis.com/v1/operations/sample1"
+        response_value.request = mock_request
+        req.return_value = response_value
+        with pytest.raises(core_exceptions.GoogleAPIError):
+            await client.get_operation("sample0/operations/sample1")
+
+
+def test_delete_operation_rest():
+    client = _get_operations_client(is_async=False)
+
+    # Mock the http request call within the method and fake a response.
+    with mock.patch.object(_get_session_type(is_async=False), "request") as req:
+        # Wrap the value into a proper Response obj
+        response_value = Response()
+        response_value.status_code = 200
+        json_return_value = ""
+        response_value._content = json_return_value.encode("UTF-8")
+        req.return_value = response_value
+        client.delete_operation(name="operations/sample1")
+        assert req.call_count == 1
+        actual_args = req.call_args
+        assert actual_args.args[0] == "DELETE"
+        assert (
+            actual_args.args[1]
+            == "https://longrunning.googleapis.com/v3/operations/sample1"
+        )
+
+
+@pytest.mark.asyncio
+async def test_delete_operation_rest_async():
+    if not GOOGLE_AUTH_AIO_INSTALLED:
+        pytest.skip("Skipped because google-api-core[async_rest] is not installed")
+    client = _get_operations_client(is_async=True)
+
+    # Mock the http request call within the method and fake a response.
+    with mock.patch.object(_get_session_type(is_async=True), "request") as req:
+        # Wrap the value into a proper Response obj
+        response_value = mock.Mock()
+        response_value.status_code = 200
+        json_return_value = ""
+        response_value.read = mock.AsyncMock(
+            return_value=json_return_value.encode("UTF-8")
+        )
+        req.return_value = response_value
+        await client.delete_operation(name="operations/sample1")
+        assert req.call_count == 1
+        actual_args = req.call_args
+        assert actual_args.args[0] == "DELETE"
+        assert (
+            actual_args.args[1]
+            == "https://longrunning.googleapis.com/v3/operations/sample1"
+        )
+
+
+def test_delete_operation_rest_failure():
+    client = _get_operations_client(is_async=False, http_options=None)
+
+    with mock.patch.object(_get_session_type(is_async=False), "request") as req:
+        response_value = Response()
+        response_value.status_code = 400
+        mock_request = mock.MagicMock()
+        mock_request.method = "DELETE"
+        mock_request.url = "https://longrunning.googleapis.com/v1/operations/sample1"
+        response_value.request = mock_request
+        req.return_value = response_value
+        with pytest.raises(core_exceptions.GoogleAPIError):
+            client.delete_operation(name="sample0/operations/sample1")
+
+
+@pytest.mark.asyncio
+async def test_delete_operation_rest_failure_async():
+    if not GOOGLE_AUTH_AIO_INSTALLED:
+        pytest.skip("Skipped because google-api-core[async_rest] is not installed")
+    client = _get_operations_client(is_async=True, http_options=None)
+
+    with mock.patch.object(_get_session_type(is_async=True), "request") as req:
+        response_value = mock.Mock()
+        response_value.status_code = 400
+        response_value.read = mock.AsyncMock(return_value=b"{}")
+        mock_request = mock.MagicMock()
+        mock_request.method = "DELETE"
+        mock_request.url = "https://longrunning.googleapis.com/v1/operations/sample1"
+        response_value.request = mock_request
+        req.return_value = response_value
+        with pytest.raises(core_exceptions.GoogleAPIError):
+            await client.delete_operation(name="sample0/operations/sample1")
+
+
+def test_cancel_operation_rest():
+    client = _get_operations_client(is_async=False)
+
+    # Mock the http request call within the method and fake a response.
+    with mock.patch.object(_get_session_type(is_async=False), "request") as req:
+        # Wrap the value into a proper Response obj
+        response_value = Response()
+        response_value.status_code = 200
+        json_return_value = ""
+        response_value._content = json_return_value.encode("UTF-8")
+        req.return_value = response_value
+        client.cancel_operation(name="operations/sample1")
+        assert req.call_count == 1
+        actual_args = req.call_args
+        assert actual_args.args[0] == "POST"
+        assert (
+            actual_args.args[1]
+            == "https://longrunning.googleapis.com/v3/operations/sample1:cancel"
+        )
+
+
+@pytest.mark.asyncio
+async def test_cancel_operation_rest_async():
+    if not GOOGLE_AUTH_AIO_INSTALLED:
+        pytest.skip("Skipped because google-api-core[async_rest] is not installed")
+    client = _get_operations_client(is_async=True)
+
+    # Mock the http request call within the method and fake a response.
+    with mock.patch.object(_get_session_type(is_async=True), "request") as req:
+        # Wrap the value into a proper Response obj
+        response_value = mock.Mock()
+        response_value.status_code = 200
+        json_return_value = ""
+        response_value.read = mock.AsyncMock(
+            return_value=json_return_value.encode("UTF-8")
+        )
+        req.return_value = response_value
+        await client.cancel_operation(name="operations/sample1")
+        assert req.call_count == 1
+        actual_args = req.call_args
+        assert actual_args.args[0] == "POST"
+        assert (
+            actual_args.args[1]
+            == "https://longrunning.googleapis.com/v3/operations/sample1:cancel"
+        )
+
+
+def test_cancel_operation_rest_failure():
+    client = _get_operations_client(is_async=False, http_options=None)
+
+    with mock.patch.object(_get_session_type(is_async=False), "request") as req:
+        response_value = Response()
+        response_value.status_code = 400
+        mock_request = mock.MagicMock()
+        mock_request.method = "POST"
+        mock_request.url = (
+            "https://longrunning.googleapis.com/v1/operations/sample1:cancel"
+        )
+        response_value.request = mock_request
+        req.return_value = response_value
+        with pytest.raises(core_exceptions.GoogleAPIError):
+            client.cancel_operation(name="sample0/operations/sample1")
+
+
+@pytest.mark.asyncio
+async def test_cancel_operation_rest_failure_async():
+    if not GOOGLE_AUTH_AIO_INSTALLED:
+        pytest.skip("Skipped because google-api-core[async_rest] is not installed")
+    client = _get_operations_client(is_async=True, http_options=None)
+
+    with mock.patch.object(_get_session_type(is_async=True), "request") as req:
+        response_value = mock.Mock()
+        response_value.status_code = 400
+        response_value.read = mock.AsyncMock(return_value=b"{}")
+        mock_request = mock.MagicMock()
+        mock_request.method = "POST"
+        mock_request.url = (
+            "https://longrunning.googleapis.com/v1/operations/sample1:cancel"
+        )
+        response_value.request = mock_request
+        req.return_value = response_value
+        with pytest.raises(core_exceptions.GoogleAPIError):
+            await client.cancel_operation(name="sample0/operations/sample1")
+
+
+@pytest.mark.parametrize(
+    "client_class,transport_class,credentials",
+    PYPARAM_CLIENT_TRANSPORT_CREDENTIALS,
+)
+def test_credentials_transport_error(client_class, transport_class, credentials):
+
+    # It is an error to provide credentials and a transport instance.
+    transport = transport_class(credentials=credentials)
+    with pytest.raises(ValueError):
+        client_class(
+            credentials=ga_credentials.AnonymousCredentials(),
+            transport=transport,
+        )
+
+    # It is an error to provide a credentials file and a transport instance.
+    transport = transport_class(credentials=credentials)
+    with pytest.raises(ValueError):
+        client_class(
+            client_options={"credentials_file": "credentials.json"},
+            transport=transport,
+        )
+
+    # It is an error to provide scopes and a transport instance.
+    transport = transport_class(credentials=credentials)
+    with pytest.raises(ValueError):
+        client_class(
+            client_options={"scopes": ["1", "2"]},
+            transport=transport,
+        )
+
+
+@pytest.mark.parametrize(
+    "client_class,transport_class,credentials",
+    PYPARAM_CLIENT_TRANSPORT_CREDENTIALS,
+)
+def test_transport_instance(client_class, transport_class, credentials):
+    # A client may be instantiated with a custom transport instance.
+    transport = transport_class(
+        credentials=credentials,
+    )
+    client = client_class(transport=transport)
+    assert client.transport is transport
+
+
+@pytest.mark.parametrize(
+    "client_class,transport_class,credentials",
+    PYPARAM_CLIENT_TRANSPORT_CREDENTIALS,
+)
+def test_transport_adc(client_class, transport_class, credentials):
+    # Test default credentials are used if not provided.
+    with mock.patch.object(google.auth, "default") as adc:
+        adc.return_value = (credentials, None)
+        transport_class()
+        adc.assert_called_once()
+
+
+def test_operations_base_transport_error():
+    # Passing both a credentials object and credentials_file should raise an error
+    with pytest.raises(core_exceptions.DuplicateCredentialArgs):
+        transports.OperationsTransport(
+            credentials=ga_credentials.AnonymousCredentials(),
+            credentials_file="credentials.json",
+        )
+
+
+def test_operations_base_transport():
+    # Instantiate the base transport.
+    with mock.patch(
+        "google.api_core.operations_v1.transports.OperationsTransport.__init__"
+    ) as Transport:
+        Transport.return_value = None
+        transport = transports.OperationsTransport(
+            credentials=ga_credentials.AnonymousCredentials(),
+        )
+
+    # Every method on the transport should just blindly
+    # raise NotImplementedError.
+    methods = (
+        "list_operations",
+        "get_operation",
+        "delete_operation",
+        "cancel_operation",
+    )
+    for method in methods:
+        with pytest.raises(NotImplementedError):
+            getattr(transport, method)(request=object())
+
+    with pytest.raises(NotImplementedError):
+        transport.close()
+
+
+def test_operations_base_transport_with_credentials_file():
+    # Instantiate the base transport with a credentials file
+    with mock.patch.object(
+        google.auth, "load_credentials_from_file", autospec=True
+    ) as load_creds, mock.patch(
+        "google.api_core.operations_v1.transports.OperationsTransport._prep_wrapped_messages"
+    ) as Transport:
+        Transport.return_value = None
+        load_creds.return_value = (ga_credentials.AnonymousCredentials(), None)
+        transports.OperationsTransport(
+            credentials_file="credentials.json",
+            quota_project_id="octopus",
+        )
+        load_creds.assert_called_once_with(
+            "credentials.json",
+            scopes=None,
+            default_scopes=(),
+            quota_project_id="octopus",
+        )
+
+
+def test_operations_base_transport_with_adc():
+    # Test the default credentials are used if credentials and credentials_file are None.
+    with mock.patch.object(google.auth, "default", autospec=True) as adc, mock.patch(
+        "google.api_core.operations_v1.transports.OperationsTransport._prep_wrapped_messages"
+    ) as Transport:
+        Transport.return_value = None
+        adc.return_value = (ga_credentials.AnonymousCredentials(), None)
+        transports.OperationsTransport()
+        adc.assert_called_once()
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_operations_auth_adc(client_class):
+    # If no credentials are provided, we should use ADC credentials.
+    with mock.patch.object(google.auth, "default", autospec=True) as adc:
+        adc.return_value = (ga_credentials.AnonymousCredentials(), None)
+
+        if "async" in str(client_class).lower():
+            # TODO(): Add support for adc to async REST transport.
+            # NOTE: Ideally, the logic for adc shouldn't be called if transport
+            # is set to async REST. If the user does not configure credentials
+            # of type `google.auth.aio.credentials.Credentials`,
+            # we should raise an exception to avoid the adc workflow.
+            with pytest.raises(google.auth.exceptions.InvalidType):
+                client_class()
+        else:
+            client_class()
+            adc.assert_called_once_with(
+                scopes=None,
+                default_scopes=(),
+                quota_project_id=None,
+            )
+
+
+# TODO(https://github.com/googleapis/python-api-core/issues/705): Add
+# testing for `transports.AsyncOperationsRestTransport` once MTLS is supported
+# in `google.auth.aio.transport`.
+@pytest.mark.parametrize(
+    "transport_class",
+    [
+        transports.OperationsRestTransport,
+    ],
+)
+def test_operations_http_transport_client_cert_source_for_mtls(transport_class):
+    cred = ga_credentials.AnonymousCredentials()
+    with mock.patch(
+        "google.auth.transport.requests.AuthorizedSession.configure_mtls_channel"
+    ) as mock_configure_mtls_channel:
+        transport_class(
+            credentials=cred, client_cert_source_for_mtls=client_cert_source_callback
+        )
+        mock_configure_mtls_channel.assert_called_once_with(client_cert_source_callback)
+
+
+@pytest.mark.parametrize(
+    "client_class,transport_class,credentials",
+    PYPARAM_CLIENT_TRANSPORT_CREDENTIALS,
+)
+def test_operations_host_no_port(client_class, transport_class, credentials):
+    client = client_class(
+        credentials=credentials,
+        client_options=client_options.ClientOptions(
+            api_endpoint="longrunning.googleapis.com"
+        ),
+    )
+    assert client.transport._host == "https://longrunning.googleapis.com"
+
+
+@pytest.mark.parametrize(
+    "client_class,transport_class,credentials",
+    PYPARAM_CLIENT_TRANSPORT_CREDENTIALS,
+)
+def test_operations_host_with_port(client_class, transport_class, credentials):
+    client = client_class(
+        credentials=credentials,
+        client_options=client_options.ClientOptions(
+            api_endpoint="longrunning.googleapis.com:8000"
+        ),
+    )
+    assert client.transport._host == "https://longrunning.googleapis.com:8000"
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_common_billing_account_path(client_class):
+    billing_account = "squid"
+    expected = "billingAccounts/{billing_account}".format(
+        billing_account=billing_account,
+    )
+    actual = client_class.common_billing_account_path(billing_account)
+    assert expected == actual
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_parse_common_billing_account_path(client_class):
+    expected = {
+        "billing_account": "clam",
+    }
+    path = client_class.common_billing_account_path(**expected)
+
+    # Check that the path construction is reversible.
+    actual = client_class.parse_common_billing_account_path(path)
+    assert expected == actual
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_common_folder_path(client_class):
+    folder = "whelk"
+    expected = "folders/{folder}".format(
+        folder=folder,
+    )
+    actual = client_class.common_folder_path(folder)
+    assert expected == actual
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_parse_common_folder_path(client_class):
+    expected = {
+        "folder": "octopus",
+    }
+    path = client_class.common_folder_path(**expected)
+
+    # Check that the path construction is reversible.
+    actual = client_class.parse_common_folder_path(path)
+    assert expected == actual
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_common_organization_path(client_class):
+    organization = "oyster"
+    expected = "organizations/{organization}".format(
+        organization=organization,
+    )
+    actual = client_class.common_organization_path(organization)
+    assert expected == actual
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_parse_common_organization_path(client_class):
+    expected = {
+        "organization": "nudibranch",
+    }
+    path = client_class.common_organization_path(**expected)
+
+    # Check that the path construction is reversible.
+    actual = client_class.parse_common_organization_path(path)
+    assert expected == actual
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_common_project_path(client_class):
+    project = "cuttlefish"
+    expected = "projects/{project}".format(
+        project=project,
+    )
+    actual = client_class.common_project_path(project)
+    assert expected == actual
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_parse_common_project_path(client_class):
+    expected = {
+        "project": "mussel",
+    }
+    path = client_class.common_project_path(**expected)
+
+    # Check that the path construction is reversible.
+    actual = client_class.parse_common_project_path(path)
+    assert expected == actual
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_common_location_path(client_class):
+    project = "winkle"
+    location = "nautilus"
+    expected = "projects/{project}/locations/{location}".format(
+        project=project,
+        location=location,
+    )
+    actual = client_class.common_location_path(project, location)
+    assert expected == actual
+
+
+@pytest.mark.parametrize(
+    "client_class",
+    PYPARAM_CLIENT,
+)
+def test_parse_common_location_path(client_class):
+    expected = {
+        "project": "scallop",
+        "location": "abalone",
+    }
+    path = client_class.common_location_path(**expected)
+
+    # Check that the path construction is reversible.
+    actual = client_class.parse_common_location_path(path)
+    assert expected == actual
+
+
+@pytest.mark.parametrize(
+    "client_class,transport_class,credentials",
+    PYPARAM_CLIENT_TRANSPORT_CREDENTIALS,
+)
+def test_client_withDEFAULT_CLIENT_INFO(client_class, transport_class, credentials):
+    client_info = gapic_v1.client_info.ClientInfo()
+    with mock.patch.object(transport_class, "_prep_wrapped_messages") as prep:
+        client_class(
+            credentials=credentials,
+            client_info=client_info,
+        )
+        prep.assert_called_once_with(client_info)
+
+    with mock.patch.object(transport_class, "_prep_wrapped_messages") as prep:
+        transport_class(
+            credentials=credentials,
+            client_info=client_info,
+        )
+        prep.assert_called_once_with(client_info)
diff --git a/tests/unit/retry/__init__.py b/tests/unit/retry/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/unit/retry/test_retry_base.py b/tests/unit/retry/test_retry_base.py
new file mode 100644
index 00000000..212c4293
--- /dev/null
+++ b/tests/unit/retry/test_retry_base.py
@@ -0,0 +1,293 @@
+# Copyright 2017 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import itertools
+import re
+from unittest import mock
+
+import pytest
+import requests.exceptions
+
+from google.api_core import exceptions
+from google.api_core import retry
+from google.auth import exceptions as auth_exceptions
+
+
+def test_if_exception_type():
+    predicate = retry.if_exception_type(ValueError)
+
+    assert predicate(ValueError())
+    assert not predicate(TypeError())
+
+
+def test_if_exception_type_multiple():
+    predicate = retry.if_exception_type(ValueError, TypeError)
+
+    assert predicate(ValueError())
+    assert predicate(TypeError())
+    assert not predicate(RuntimeError())
+
+
+def test_if_transient_error():
+    assert retry.if_transient_error(exceptions.InternalServerError(""))
+    assert retry.if_transient_error(exceptions.TooManyRequests(""))
+    assert retry.if_transient_error(exceptions.ServiceUnavailable(""))
+    assert retry.if_transient_error(requests.exceptions.ConnectionError(""))
+    assert retry.if_transient_error(requests.exceptions.ChunkedEncodingError(""))
+    assert retry.if_transient_error(auth_exceptions.TransportError(""))
+    assert not retry.if_transient_error(exceptions.InvalidArgument(""))
+
+
+# Make uniform return half of its maximum, which will be the calculated
+# sleep time.
+@mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n)
+def test_exponential_sleep_generator_base_2(uniform):
+    gen = retry.exponential_sleep_generator(1, 60, multiplier=2)
+
+    result = list(itertools.islice(gen, 8))
+    assert result == [1, 2, 4, 8, 16, 32, 60, 60]
+
+
+def test_build_retry_error_empty_list():
+    """
+    attempt to build a retry error with no errors encountered
+    should return a generic RetryError
+    """
+    from google.api_core.retry import build_retry_error
+    from google.api_core.retry import RetryFailureReason
+
+    reason = RetryFailureReason.NON_RETRYABLE_ERROR
+    src, cause = build_retry_error([], reason, 10)
+    assert isinstance(src, exceptions.RetryError)
+    assert cause is None
+    assert src.message == "Unknown error"
+
+
+def test_build_retry_error_timeout_message():
+    """
+    should provide helpful error message when timeout is reached
+    """
+    from google.api_core.retry import build_retry_error
+    from google.api_core.retry import RetryFailureReason
+
+    reason = RetryFailureReason.TIMEOUT
+    cause = RuntimeError("timeout")
+    src, found_cause = build_retry_error([ValueError(), cause], reason, 10)
+    assert isinstance(src, exceptions.RetryError)
+    assert src.message == "Timeout of 10.0s exceeded"
+    # should attach appropriate cause
+    assert found_cause is cause
+
+
+def test_build_retry_error_empty_timeout():
+    """
+    attempt to build a retry error when timeout is None
+    should return a generic timeout error message
+    """
+    from google.api_core.retry import build_retry_error
+    from google.api_core.retry import RetryFailureReason
+
+    reason = RetryFailureReason.TIMEOUT
+    src, _ = build_retry_error([], reason, None)
+    assert isinstance(src, exceptions.RetryError)
+    assert src.message == "Timeout exceeded"
+
+
+class Test_BaseRetry(object):
+    def _make_one(self, *args, **kwargs):
+        return retry.retry_base._BaseRetry(*args, **kwargs)
+
+    def test_constructor_defaults(self):
+        retry_ = self._make_one()
+        assert retry_._predicate == retry.if_transient_error
+        assert retry_._initial == 1
+        assert retry_._maximum == 60
+        assert retry_._multiplier == 2
+        assert retry_._timeout == 120
+        assert retry_._on_error is None
+        assert retry_.timeout == 120
+        assert retry_.timeout == 120
+
+    def test_constructor_options(self):
+        _some_function = mock.Mock()
+
+        retry_ = self._make_one(
+            predicate=mock.sentinel.predicate,
+            initial=1,
+            maximum=2,
+            multiplier=3,
+            timeout=4,
+            on_error=_some_function,
+        )
+        assert retry_._predicate == mock.sentinel.predicate
+        assert retry_._initial == 1
+        assert retry_._maximum == 2
+        assert retry_._multiplier == 3
+        assert retry_._timeout == 4
+        assert retry_._on_error is _some_function
+
+    @pytest.mark.parametrize("use_deadline", [True, False])
+    @pytest.mark.parametrize("value", [None, 0, 1, 4, 42, 5.5])
+    def test_with_timeout(self, use_deadline, value):
+        retry_ = self._make_one(
+            predicate=mock.sentinel.predicate,
+            initial=1,
+            maximum=2,
+            multiplier=3,
+            timeout=4,
+            on_error=mock.sentinel.on_error,
+        )
+        new_retry = (
+            retry_.with_timeout(value)
+            if not use_deadline
+            else retry_.with_deadline(value)
+        )
+        assert retry_ is not new_retry
+        assert new_retry._timeout == value
+        assert (
+            new_retry.timeout == value
+            if not use_deadline
+            else new_retry.deadline == value
+        )
+
+        # the rest of the attributes should remain the same
+        assert new_retry._predicate is retry_._predicate
+        assert new_retry._initial == retry_._initial
+        assert new_retry._maximum == retry_._maximum
+        assert new_retry._multiplier == retry_._multiplier
+        assert new_retry._on_error is retry_._on_error
+
+    def test_with_predicate(self):
+        retry_ = self._make_one(
+            predicate=mock.sentinel.predicate,
+            initial=1,
+            maximum=2,
+            multiplier=3,
+            timeout=4,
+            on_error=mock.sentinel.on_error,
+        )
+        new_retry = retry_.with_predicate(mock.sentinel.predicate)
+        assert retry_ is not new_retry
+        assert new_retry._predicate == mock.sentinel.predicate
+
+        # the rest of the attributes should remain the same
+        assert new_retry._timeout == retry_._timeout
+        assert new_retry._initial == retry_._initial
+        assert new_retry._maximum == retry_._maximum
+        assert new_retry._multiplier == retry_._multiplier
+        assert new_retry._on_error is retry_._on_error
+
+    def test_with_delay_noop(self):
+        retry_ = self._make_one(
+            predicate=mock.sentinel.predicate,
+            initial=1,
+            maximum=2,
+            multiplier=3,
+            timeout=4,
+            on_error=mock.sentinel.on_error,
+        )
+        new_retry = retry_.with_delay()
+        assert retry_ is not new_retry
+        assert new_retry._initial == retry_._initial
+        assert new_retry._maximum == retry_._maximum
+        assert new_retry._multiplier == retry_._multiplier
+
+    @pytest.mark.parametrize(
+        "originals,updated,expected",
+        [
+            [(1, 2, 3), (4, 5, 6), (4, 5, 6)],
+            [(1, 2, 3), (0, 0, 0), (0, 0, 0)],
+            [(1, 2, 3), (None, None, None), (1, 2, 3)],
+            [(0, 0, 0), (None, None, None), (0, 0, 0)],
+            [(1, 2, 3), (None, 0.5, None), (1, 0.5, 3)],
+            [(1, 2, 3), (None, 0.5, 4), (1, 0.5, 4)],
+            [(1, 2, 3), (9, None, None), (9, 2, 3)],
+        ],
+    )
+    def test_with_delay(self, originals, updated, expected):
+        retry_ = self._make_one(
+            predicate=mock.sentinel.predicate,
+            initial=originals[0],
+            maximum=originals[1],
+            multiplier=originals[2],
+            timeout=14,
+            on_error=mock.sentinel.on_error,
+        )
+        new_retry = retry_.with_delay(
+            initial=updated[0], maximum=updated[1], multiplier=updated[2]
+        )
+        assert retry_ is not new_retry
+        assert new_retry._initial == expected[0]
+        assert new_retry._maximum == expected[1]
+        assert new_retry._multiplier == expected[2]
+
+        # the rest of the attributes should remain the same
+        assert new_retry._timeout == retry_._timeout
+        assert new_retry._predicate is retry_._predicate
+        assert new_retry._on_error is retry_._on_error
+
+    def test_with_delay_partial_options(self):
+        retry_ = self._make_one(
+            predicate=mock.sentinel.predicate,
+            initial=1,
+            maximum=2,
+            multiplier=3,
+            timeout=4,
+            on_error=mock.sentinel.on_error,
+        )
+        new_retry = retry_.with_delay(initial=4)
+        assert retry_ is not new_retry
+        assert new_retry._initial == 4
+        assert new_retry._maximum == 2
+        assert new_retry._multiplier == 3
+
+        new_retry = retry_.with_delay(maximum=4)
+        assert retry_ is not new_retry
+        assert new_retry._initial == 1
+        assert new_retry._maximum == 4
+        assert new_retry._multiplier == 3
+
+        new_retry = retry_.with_delay(multiplier=4)
+        assert retry_ is not new_retry
+        assert new_retry._initial == 1
+        assert new_retry._maximum == 2
+        assert new_retry._multiplier == 4
+
+        # the rest of the attributes should remain the same
+        assert new_retry._timeout == retry_._timeout
+        assert new_retry._predicate is retry_._predicate
+        assert new_retry._on_error is retry_._on_error
+
+    def test___str__(self):
+        def if_exception_type(exc):
+            return bool(exc)  # pragma: NO COVER
+
+        # Explicitly set all attributes as changed Retry defaults should not
+        # cause this test to start failing.
+        retry_ = self._make_one(
+            predicate=if_exception_type,
+            initial=1.0,
+            maximum=60.0,
+            multiplier=2.0,
+            timeout=120.0,
+            on_error=None,
+        )
+        assert re.match(
+            (
+                r"<_BaseRetry predicate=<function.*?if_exception_type.*?>, "
+                r"initial=1.0, maximum=60.0, multiplier=2.0, timeout=120.0, "
+                r"on_error=None>"
+            ),
+            str(retry_),
+        )
diff --git a/tests/unit/retry/test_retry_imports.py b/tests/unit/retry/test_retry_imports.py
new file mode 100644
index 00000000..597909fc
--- /dev/null
+++ b/tests/unit/retry/test_retry_imports.py
@@ -0,0 +1,33 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+def test_legacy_imports_retry_unary_sync():
+    # TODO: Delete this test when when we revert these imports on the
+    #       next major version release
+    #       (https://github.com/googleapis/python-api-core/issues/576)
+    from google.api_core.retry import datetime_helpers  # noqa: F401
+    from google.api_core.retry import exceptions  # noqa: F401
+    from google.api_core.retry import auth_exceptions  # noqa: F401
+
+
+def test_legacy_imports_retry_unary_async():
+    # TODO: Delete this test when when we revert these imports on the
+    #       next major version release
+    #       (https://github.com/googleapis/python-api-core/issues/576)
+    from google.api_core import retry_async  # noqa: F401
+
+    # See https://github.com/googleapis/python-api-core/issues/586
+    # for context on why we need to test this import this explicitly.
+    from google.api_core.retry_async import AsyncRetry  # noqa: F401
diff --git a/tests/unit/retry/test_retry_streaming.py b/tests/unit/retry/test_retry_streaming.py
new file mode 100644
index 00000000..2499b2ae
--- /dev/null
+++ b/tests/unit/retry/test_retry_streaming.py
@@ -0,0 +1,505 @@
+# Copyright 2017 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import re
+
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock  # pragma: NO COVER  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    import mock  # type: ignore
+
+import pytest
+
+from google.api_core import exceptions
+from google.api_core import retry
+from google.api_core.retry import retry_streaming
+
+from .test_retry_base import Test_BaseRetry
+
+
+def test_retry_streaming_target_bad_sleep_generator():
+    with pytest.raises(
+        ValueError, match="Sleep generator stopped yielding sleep values"
+    ):
+        next(retry_streaming.retry_target_stream(None, lambda x: True, [], None))
+
+
+@mock.patch("time.sleep", autospec=True)
+def test_retry_streaming_target_dynamic_backoff(sleep):
+    """
+    sleep_generator should be iterated after on_error, to support dynamic backoff
+    """
+    from functools import partial
+
+    sleep.side_effect = RuntimeError("stop after sleep")
+    # start with empty sleep generator; values are added after exception in push_sleep_value
+    sleep_values = []
+    error_target = partial(TestStreamingRetry._generator_mock, error_on=0)
+    inserted_sleep = 99
+
+    def push_sleep_value(err):
+        sleep_values.append(inserted_sleep)
+
+    with pytest.raises(RuntimeError):
+        next(
+            retry_streaming.retry_target_stream(
+                error_target,
+                predicate=lambda x: True,
+                sleep_generator=sleep_values,
+                on_error=push_sleep_value,
+            )
+        )
+    assert sleep.call_count == 1
+    sleep.assert_called_once_with(inserted_sleep)
+
+
+class TestStreamingRetry(Test_BaseRetry):
+    def _make_one(self, *args, **kwargs):
+        return retry_streaming.StreamingRetry(*args, **kwargs)
+
+    def test___str__(self):
+        def if_exception_type(exc):
+            return bool(exc)  # pragma: NO COVER
+
+        # Explicitly set all attributes as changed Retry defaults should not
+        # cause this test to start failing.
+        retry_ = retry_streaming.StreamingRetry(
+            predicate=if_exception_type,
+            initial=1.0,
+            maximum=60.0,
+            multiplier=2.0,
+            timeout=120.0,
+            on_error=None,
+        )
+        assert re.match(
+            (
+                r"<StreamingRetry predicate=<function.*?if_exception_type.*?>, "
+                r"initial=1.0, maximum=60.0, multiplier=2.0, timeout=120.0, "
+                r"on_error=None>"
+            ),
+            str(retry_),
+        )
+
+    @staticmethod
+    def _generator_mock(
+        num=5,
+        error_on=None,
+        return_val=None,
+        exceptions_seen=None,
+    ):
+        """
+        Helper to create a mock generator that yields a number of values
+        Generator can optionally raise an exception on a specific iteration
+
+        Args:
+          - num (int): the number of values to yield. After this, the generator will return `return_val`
+          - error_on (int): if given, the generator will raise a ValueError on the specified iteration
+          - return_val (any): if given, the generator will return this value after yielding num values
+          - exceptions_seen (list): if given, the generator will append any exceptions to this list before raising
+        """
+        try:
+            for i in range(num):
+                if error_on is not None and i == error_on:
+                    raise ValueError("generator mock error")
+                yield i
+            return return_val
+        except (Exception, BaseException, GeneratorExit) as e:
+            # keep track of exceptions seen by generator
+            if exceptions_seen is not None:
+                exceptions_seen.append(e)
+            raise
+
+    @mock.patch("time.sleep", autospec=True)
+    def test___call___success(self, sleep):
+        """
+        Test that a retry-decorated generator yields values as expected
+        This test checks a generator with no issues
+        """
+        import types
+        import collections
+
+        retry_ = retry_streaming.StreamingRetry()
+
+        decorated = retry_(self._generator_mock)
+
+        num = 10
+        result = decorated(num)
+        # check types
+        assert isinstance(decorated(num), collections.abc.Iterable)
+        assert isinstance(decorated(num), types.GeneratorType)
+        assert isinstance(self._generator_mock(num), collections.abc.Iterable)
+        assert isinstance(self._generator_mock(num), types.GeneratorType)
+        # check yield contents
+        unpacked = [i for i in result]
+        assert len(unpacked) == num
+        for a, b in zip(unpacked, self._generator_mock(num)):
+            assert a == b
+        sleep.assert_not_called()
+
+    @mock.patch("time.sleep", autospec=True)
+    def test___call___retry(self, sleep):
+        """
+        Tests that a retry-decorated generator will retry on errors
+        """
+        on_error = mock.Mock(return_value=None)
+        retry_ = retry_streaming.StreamingRetry(
+            on_error=on_error,
+            predicate=retry.if_exception_type(ValueError),
+            timeout=None,
+        )
+        result = retry_(self._generator_mock)(error_on=3)
+        # error thrown on 3
+        # generator should contain 0, 1, 2 looping
+        unpacked = [next(result) for i in range(10)]
+        assert unpacked == [0, 1, 2, 0, 1, 2, 0, 1, 2, 0]
+        assert on_error.call_count == 3
+
+    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n)
+    @mock.patch("time.sleep", autospec=True)
+    @pytest.mark.parametrize("use_deadline_arg", [True, False])
+    def test___call___retry_hitting_timeout(self, sleep, uniform, use_deadline_arg):
+        """
+        Tests that a retry-decorated generator will throw a RetryError
+        after using the time budget
+        """
+        import time
+
+        timeout_val = 30.9
+        # support "deadline" as an alias for "timeout"
+        timeout_kwarg = (
+            {"timeout": timeout_val}
+            if not use_deadline_arg
+            else {"deadline": timeout_val}
+        )
+
+        on_error = mock.Mock(return_value=None)
+        retry_ = retry_streaming.StreamingRetry(
+            predicate=retry.if_exception_type(ValueError),
+            initial=1.0,
+            maximum=1024.0,
+            multiplier=2.0,
+            **timeout_kwarg,
+        )
+
+        timenow = time.monotonic()
+        now_patcher = mock.patch(
+            "time.monotonic",
+            return_value=timenow,
+        )
+
+        decorated = retry_(self._generator_mock, on_error=on_error)
+        generator = decorated(error_on=1)
+        with now_patcher as patched_now:
+            # Make sure that calls to fake time.sleep() also advance the mocked
+            # time clock.
+            def increase_time(sleep_delay):
+                patched_now.return_value += sleep_delay
+
+            sleep.side_effect = increase_time
+            with pytest.raises(exceptions.RetryError):
+                [i for i in generator]
+
+        assert on_error.call_count == 5
+        # check the delays
+        assert sleep.call_count == 4  # once between each successive target calls
+        last_wait = sleep.call_args.args[0]
+        total_wait = sum(call_args.args[0] for call_args in sleep.call_args_list)
+        assert last_wait == 8.0
+        assert total_wait == 15.0
+
+    @mock.patch("time.sleep", autospec=True)
+    def test___call___with_generator_send(self, sleep):
+        """
+        Send should be passed through retry into target generator
+        """
+
+        def _mock_send_gen():
+            """
+            always yield whatever was sent in
+            """
+            in_ = yield
+            while True:
+                in_ = yield in_
+
+        retry_ = retry_streaming.StreamingRetry()
+
+        decorated = retry_(_mock_send_gen)
+
+        generator = decorated()
+        result = next(generator)
+        # first yield should be None
+        assert result is None
+        in_messages = ["test_1", "hello", "world"]
+        out_messages = []
+        for msg in in_messages:
+            recv = generator.send(msg)
+            out_messages.append(recv)
+        assert in_messages == out_messages
+
+    @mock.patch("time.sleep", autospec=True)
+    def test___call___with_generator_send_retry(self, sleep):
+        """
+        Send should support retries like next
+        """
+        on_error = mock.Mock(return_value=None)
+        retry_ = retry_streaming.StreamingRetry(
+            on_error=on_error,
+            predicate=retry.if_exception_type(ValueError),
+            timeout=None,
+        )
+        result = retry_(self._generator_mock)(error_on=3)
+        with pytest.raises(TypeError) as exc_info:
+            # calling first send with non-None input should raise a TypeError
+            result.send("can not send to fresh generator")
+            assert exc_info.match("can't send non-None value")
+        # initiate iteration with None
+        result = retry_(self._generator_mock)(error_on=3)
+        assert result.send(None) == 0
+        # error thrown on 3
+        # generator should contain 0, 1, 2 looping
+        unpacked = [result.send(i) for i in range(10)]
+        assert unpacked == [1, 2, 0, 1, 2, 0, 1, 2, 0, 1]
+        assert on_error.call_count == 3
+
+    @mock.patch("time.sleep", autospec=True)
+    def test___call___with_iterable_send(self, sleep):
+        """
+        send should raise attribute error if wrapped iterator does not support it
+        """
+        retry_ = retry_streaming.StreamingRetry()
+
+        def iterable_fn(n):
+            return iter(range(n))
+
+        decorated = retry_(iterable_fn)
+        generator = decorated(5)
+        # initialize
+        next(generator)
+        # call send
+        with pytest.raises(AttributeError):
+            generator.send("test")
+
+    @mock.patch("time.sleep", autospec=True)
+    def test___call___with_iterable_close(self, sleep):
+        """
+        close should be handled by wrapper if wrapped iterable does not support it
+        """
+        retry_ = retry_streaming.StreamingRetry()
+
+        def iterable_fn(n):
+            return iter(range(n))
+
+        decorated = retry_(iterable_fn)
+
+        # try closing active generator
+        retryable = decorated(10)
+        assert next(retryable) == 0
+        retryable.close()
+        with pytest.raises(StopIteration):
+            next(retryable)
+
+        # try closing a new generator
+        retryable = decorated(10)
+        retryable.close()
+        with pytest.raises(StopIteration):
+            next(retryable)
+
+    @mock.patch("time.sleep", autospec=True)
+    def test___call___with_iterable_throw(self, sleep):
+        """
+        Throw should work even if the wrapped iterable does not support it
+        """
+        predicate = retry.if_exception_type(ValueError)
+        retry_ = retry_streaming.StreamingRetry(predicate=predicate)
+
+        def iterable_fn(n):
+            return iter(range(n))
+
+        decorated = retry_(iterable_fn)
+
+        # try throwing with active generator
+        retryable = decorated(10)
+        assert next(retryable) == 0
+        # should swallow errors in predicate
+        retryable.throw(ValueError)
+        assert next(retryable) == 1
+        # should raise on other errors
+        with pytest.raises(TypeError):
+            retryable.throw(TypeError)
+        with pytest.raises(StopIteration):
+            next(retryable)
+
+        # try throwing with a new generator
+        retryable = decorated(10)
+        with pytest.raises(ValueError):
+            retryable.throw(ValueError)
+        with pytest.raises(StopIteration):
+            next(retryable)
+
+    @mock.patch("time.sleep", autospec=True)
+    def test___call___with_generator_return(self, sleep):
+        """
+        Generator return value should be passed through retry decorator
+        """
+        retry_ = retry_streaming.StreamingRetry()
+
+        decorated = retry_(self._generator_mock)
+
+        expected_value = "done"
+        generator = decorated(5, return_val=expected_value)
+        found_value = None
+        try:
+            while True:
+                next(generator)
+        except StopIteration as e:
+            found_value = e.value
+        assert found_value == expected_value
+
+    @mock.patch("time.sleep", autospec=True)
+    def test___call___with_generator_close(self, sleep):
+        """
+        Close should be passed through retry into target generator
+        """
+        retry_ = retry_streaming.StreamingRetry()
+
+        decorated = retry_(self._generator_mock)
+
+        exception_list = []
+        generator = decorated(10, exceptions_seen=exception_list)
+        for i in range(2):
+            next(generator)
+        generator.close()
+        assert isinstance(exception_list[0], GeneratorExit)
+        with pytest.raises(StopIteration):
+            # calling next on closed generator should raise error
+            next(generator)
+
+    @mock.patch("time.sleep", autospec=True)
+    def test___call___with_generator_throw(self, sleep):
+        """
+        Throw should be passed through retry into target generator
+        """
+        retry_ = retry_streaming.StreamingRetry(
+            predicate=retry.if_exception_type(ValueError),
+        )
+        decorated = retry_(self._generator_mock)
+
+        exception_list = []
+        generator = decorated(10, exceptions_seen=exception_list)
+        for i in range(2):
+            next(generator)
+        with pytest.raises(BufferError):
+            generator.throw(BufferError("test"))
+        assert isinstance(exception_list[0], BufferError)
+        with pytest.raises(StopIteration):
+            # calling next on closed generator should raise error
+            next(generator)
+        # should retry if throw retryable exception
+        exception_list = []
+        generator = decorated(10, exceptions_seen=exception_list)
+        for i in range(2):
+            next(generator)
+        val = generator.throw(ValueError("test"))
+        assert val == 0
+        assert isinstance(exception_list[0], ValueError)
+        # calling next on closed generator should not raise error
+        assert next(generator) == 1
+
+    def test_exc_factory_non_retryable_error(self):
+        """
+        generator should give the option to override exception creation logic
+        test when non-retryable error is thrown
+        """
+        from google.api_core.retry import RetryFailureReason
+        from google.api_core.retry.retry_streaming import retry_target_stream
+
+        timeout = None
+        sent_errors = [ValueError("test"), ValueError("test2"), BufferError("test3")]
+        expected_final_err = RuntimeError("done")
+        expected_source_err = ZeroDivisionError("test4")
+
+        def factory(*args, **kwargs):
+            assert len(kwargs) == 0
+            assert args[0] == sent_errors
+            assert args[1] == RetryFailureReason.NON_RETRYABLE_ERROR
+            assert args[2] == timeout
+            return expected_final_err, expected_source_err
+
+        generator = retry_target_stream(
+            self._generator_mock,
+            retry.if_exception_type(ValueError),
+            [0] * 3,
+            timeout=timeout,
+            exception_factory=factory,
+        )
+        # initialize generator
+        next(generator)
+        # trigger some retryable errors
+        generator.throw(sent_errors[0])
+        generator.throw(sent_errors[1])
+        # trigger a non-retryable error
+        with pytest.raises(expected_final_err.__class__) as exc_info:
+            generator.throw(sent_errors[2])
+        assert exc_info.value == expected_final_err
+        assert exc_info.value.__cause__ == expected_source_err
+
+    def test_exc_factory_timeout(self):
+        """
+        generator should give the option to override exception creation logic
+        test when timeout is exceeded
+        """
+        import time
+        from google.api_core.retry import RetryFailureReason
+        from google.api_core.retry.retry_streaming import retry_target_stream
+
+        timeout = 2
+        time_now = time.monotonic()
+        now_patcher = mock.patch(
+            "time.monotonic",
+            return_value=time_now,
+        )
+
+        with now_patcher as patched_now:
+            timeout = 2
+            sent_errors = [ValueError("test"), ValueError("test2"), ValueError("test3")]
+            expected_final_err = RuntimeError("done")
+            expected_source_err = ZeroDivisionError("test4")
+
+            def factory(*args, **kwargs):
+                assert len(kwargs) == 0
+                assert args[0] == sent_errors
+                assert args[1] == RetryFailureReason.TIMEOUT
+                assert args[2] == timeout
+                return expected_final_err, expected_source_err
+
+            generator = retry_target_stream(
+                self._generator_mock,
+                retry.if_exception_type(ValueError),
+                [0] * 3,
+                timeout=timeout,
+                exception_factory=factory,
+                check_timeout_on_yield=True,
+            )
+            # initialize generator
+            next(generator)
+            # trigger some retryable errors
+            generator.throw(sent_errors[0])
+            generator.throw(sent_errors[1])
+            # trigger a timeout
+            patched_now.return_value += timeout + 1
+            with pytest.raises(expected_final_err.__class__) as exc_info:
+                generator.throw(sent_errors[2])
+            assert exc_info.value == expected_final_err
+            assert exc_info.value.__cause__ == expected_source_err
diff --git a/tests/unit/test_retry.py b/tests/unit/retry/test_retry_unary.py
similarity index 51%
rename from tests/unit/test_retry.py
rename to tests/unit/retry/test_retry_unary.py
index 199ca559..f5bbcff7 100644
--- a/tests/unit/test_retry.py
+++ b/tests/unit/retry/test_retry_unary.py
@@ -13,51 +13,19 @@
 # limitations under the License.
 
 import datetime
-import itertools
+import pytest
 import re
 
-import mock
-import pytest
-import requests.exceptions
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock  # pragma: NO COVER  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    import mock  # type: ignore
 
 from google.api_core import exceptions
 from google.api_core import retry
-from google.auth import exceptions as auth_exceptions
-
-
-def test_if_exception_type():
-    predicate = retry.if_exception_type(ValueError)
-
-    assert predicate(ValueError())
-    assert not predicate(TypeError())
-
-
-def test_if_exception_type_multiple():
-    predicate = retry.if_exception_type(ValueError, TypeError)
-
-    assert predicate(ValueError())
-    assert predicate(TypeError())
-    assert not predicate(RuntimeError())
-
-
-def test_if_transient_error():
-    assert retry.if_transient_error(exceptions.InternalServerError(""))
-    assert retry.if_transient_error(exceptions.TooManyRequests(""))
-    assert retry.if_transient_error(exceptions.ServiceUnavailable(""))
-    assert retry.if_transient_error(requests.exceptions.ConnectionError(""))
-    assert retry.if_transient_error(requests.exceptions.ChunkedEncodingError(""))
-    assert retry.if_transient_error(auth_exceptions.TransportError(""))
-    assert not retry.if_transient_error(exceptions.InvalidArgument(""))
-
 
-# Make uniform return half of its maximum, which will be the calculated
-# sleep time.
-@mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n / 2.0)
-def test_exponential_sleep_generator_base_2(uniform):
-    gen = retry.exponential_sleep_generator(1, 60, multiplier=2)
-
-    result = list(itertools.islice(gen, 8))
-    assert result == [1, 2, 4, 8, 16, 32, 60, 60]
+from .test_retry_base import Test_BaseRetry
 
 
 @mock.patch("time.sleep", autospec=True)
@@ -129,170 +97,87 @@ def test_retry_target_non_retryable_error(utcnow, sleep):
     sleep.assert_not_called()
 
 
+@mock.patch("asyncio.sleep", autospec=True)
+@mock.patch(
+    "google.api_core.datetime_helpers.utcnow",
+    return_value=datetime.datetime.min,
+    autospec=True,
+)
+@pytest.mark.asyncio
+async def test_retry_target_warning_for_retry(utcnow, sleep):
+    predicate = retry.if_exception_type(ValueError)
+    target = mock.AsyncMock(spec=["__call__"])
+
+    with pytest.warns(Warning) as exc_info:
+        # Note: predicate is just a filler and doesn't affect the test
+        retry.retry_target(target, predicate, range(10), None)
+
+    assert len(exc_info) == 2
+    assert str(exc_info[0].message) == retry.retry_unary._ASYNC_RETRY_WARNING
+    sleep.assert_not_called()
+
+
 @mock.patch("time.sleep", autospec=True)
-@mock.patch("google.api_core.datetime_helpers.utcnow", autospec=True)
-def test_retry_target_deadline_exceeded(utcnow, sleep):
+@mock.patch("time.monotonic", autospec=True)
+@pytest.mark.parametrize("use_deadline_arg", [True, False])
+def test_retry_target_timeout_exceeded(monotonic, sleep, use_deadline_arg):
     predicate = retry.if_exception_type(ValueError)
     exception = ValueError("meep")
     target = mock.Mock(side_effect=exception)
     # Setup the timeline so that the first call takes 5 seconds but the second
-    # call takes 6, which puts the retry over the deadline.
-    utcnow.side_effect = [
-        # The first call to utcnow establishes the start of the timeline.
-        datetime.datetime.min,
-        datetime.datetime.min + datetime.timedelta(seconds=5),
-        datetime.datetime.min + datetime.timedelta(seconds=11),
-    ]
+    # call takes 6, which puts the retry over the timeout.
+    monotonic.side_effect = [0, 5, 11]
+
+    # support "deadline" as an alias for "timeout"
+    kwargs = {"timeout": 10} if not use_deadline_arg else {"deadline": 10}
 
     with pytest.raises(exceptions.RetryError) as exc_info:
-        retry.retry_target(target, predicate, range(10), deadline=10)
+        retry.retry_target(target, predicate, range(10), **kwargs)
 
     assert exc_info.value.cause == exception
-    assert exc_info.match("Deadline of 10.0s exceeded")
+    assert exc_info.match("Timeout of 10.0s exceeded")
     assert exc_info.match("last exception: meep")
     assert target.call_count == 2
 
+    # Ensure the exception message does not include the target fn:
+    # it may be a partial with user data embedded
+    assert str(target) not in exc_info.exconly()
+
 
 def test_retry_target_bad_sleep_generator():
     with pytest.raises(ValueError, match="Sleep generator"):
-        retry.retry_target(mock.sentinel.target, mock.sentinel.predicate, [], None)
-
+        retry.retry_target(mock.sentinel.target, lambda x: True, [], None)
 
-class TestRetry(object):
-    def test_constructor_defaults(self):
-        retry_ = retry.Retry()
-        assert retry_._predicate == retry.if_transient_error
-        assert retry_._initial == 1
-        assert retry_._maximum == 60
-        assert retry_._multiplier == 2
-        assert retry_._deadline == 120
-        assert retry_._on_error is None
-        assert retry_.deadline == 120
-
-    def test_constructor_options(self):
-        _some_function = mock.Mock()
 
-        retry_ = retry.Retry(
-            predicate=mock.sentinel.predicate,
-            initial=1,
-            maximum=2,
-            multiplier=3,
-            deadline=4,
-            on_error=_some_function,
+@mock.patch("time.sleep", autospec=True)
+def test_retry_target_dynamic_backoff(sleep):
+    """
+    sleep_generator should be iterated after on_error, to support dynamic backoff
+    """
+    sleep.side_effect = RuntimeError("stop after sleep")
+    # start with empty sleep generator; values are added after exception in push_sleep_value
+    sleep_values = []
+    exception = ValueError("trigger retry")
+    error_target = mock.Mock(side_effect=exception)
+    inserted_sleep = 99
+
+    def push_sleep_value(err):
+        sleep_values.append(inserted_sleep)
+
+    with pytest.raises(RuntimeError):
+        retry.retry_target(
+            error_target,
+            predicate=lambda x: True,
+            sleep_generator=sleep_values,
+            on_error=push_sleep_value,
         )
-        assert retry_._predicate == mock.sentinel.predicate
-        assert retry_._initial == 1
-        assert retry_._maximum == 2
-        assert retry_._multiplier == 3
-        assert retry_._deadline == 4
-        assert retry_._on_error is _some_function
+    assert sleep.call_count == 1
+    sleep.assert_called_once_with(inserted_sleep)
 
-    def test_with_deadline(self):
-        retry_ = retry.Retry(
-            predicate=mock.sentinel.predicate,
-            initial=1,
-            maximum=2,
-            multiplier=3,
-            deadline=4,
-            on_error=mock.sentinel.on_error,
-        )
-        new_retry = retry_.with_deadline(42)
-        assert retry_ is not new_retry
-        assert new_retry._deadline == 42
-
-        # the rest of the attributes should remain the same
-        assert new_retry._predicate is retry_._predicate
-        assert new_retry._initial == retry_._initial
-        assert new_retry._maximum == retry_._maximum
-        assert new_retry._multiplier == retry_._multiplier
-        assert new_retry._on_error is retry_._on_error
-
-    def test_with_predicate(self):
-        retry_ = retry.Retry(
-            predicate=mock.sentinel.predicate,
-            initial=1,
-            maximum=2,
-            multiplier=3,
-            deadline=4,
-            on_error=mock.sentinel.on_error,
-        )
-        new_retry = retry_.with_predicate(mock.sentinel.predicate)
-        assert retry_ is not new_retry
-        assert new_retry._predicate == mock.sentinel.predicate
-
-        # the rest of the attributes should remain the same
-        assert new_retry._deadline == retry_._deadline
-        assert new_retry._initial == retry_._initial
-        assert new_retry._maximum == retry_._maximum
-        assert new_retry._multiplier == retry_._multiplier
-        assert new_retry._on_error is retry_._on_error
-
-    def test_with_delay_noop(self):
-        retry_ = retry.Retry(
-            predicate=mock.sentinel.predicate,
-            initial=1,
-            maximum=2,
-            multiplier=3,
-            deadline=4,
-            on_error=mock.sentinel.on_error,
-        )
-        new_retry = retry_.with_delay()
-        assert retry_ is not new_retry
-        assert new_retry._initial == retry_._initial
-        assert new_retry._maximum == retry_._maximum
-        assert new_retry._multiplier == retry_._multiplier
 
-    def test_with_delay(self):
-        retry_ = retry.Retry(
-            predicate=mock.sentinel.predicate,
-            initial=1,
-            maximum=2,
-            multiplier=3,
-            deadline=4,
-            on_error=mock.sentinel.on_error,
-        )
-        new_retry = retry_.with_delay(initial=5, maximum=6, multiplier=7)
-        assert retry_ is not new_retry
-        assert new_retry._initial == 5
-        assert new_retry._maximum == 6
-        assert new_retry._multiplier == 7
-
-        # the rest of the attributes should remain the same
-        assert new_retry._deadline == retry_._deadline
-        assert new_retry._predicate is retry_._predicate
-        assert new_retry._on_error is retry_._on_error
-
-    def test_with_delay_partial_options(self):
-        retry_ = retry.Retry(
-            predicate=mock.sentinel.predicate,
-            initial=1,
-            maximum=2,
-            multiplier=3,
-            deadline=4,
-            on_error=mock.sentinel.on_error,
-        )
-        new_retry = retry_.with_delay(initial=4)
-        assert retry_ is not new_retry
-        assert new_retry._initial == 4
-        assert new_retry._maximum == 2
-        assert new_retry._multiplier == 3
-
-        new_retry = retry_.with_delay(maximum=4)
-        assert retry_ is not new_retry
-        assert new_retry._initial == 1
-        assert new_retry._maximum == 4
-        assert new_retry._multiplier == 3
-
-        new_retry = retry_.with_delay(multiplier=4)
-        assert retry_ is not new_retry
-        assert new_retry._initial == 1
-        assert new_retry._maximum == 2
-        assert new_retry._multiplier == 4
-
-        # the rest of the attributes should remain the same
-        assert new_retry._deadline == retry_._deadline
-        assert new_retry._predicate is retry_._predicate
-        assert new_retry._on_error is retry_._on_error
+class TestRetry(Test_BaseRetry):
+    def _make_one(self, *args, **kwargs):
+        return retry.Retry(*args, **kwargs)
 
     def test___str__(self):
         def if_exception_type(exc):
@@ -305,13 +190,13 @@ def if_exception_type(exc):
             initial=1.0,
             maximum=60.0,
             multiplier=2.0,
-            deadline=120.0,
+            timeout=120.0,
             on_error=None,
         )
         assert re.match(
             (
                 r"<Retry predicate=<function.*?if_exception_type.*?>, "
-                r"initial=1.0, maximum=60.0, multiplier=2.0, deadline=120.0, "
+                r"initial=1.0, maximum=60.0, multiplier=2.0, timeout=120.0, "
                 r"on_error=None>"
             ),
             str(retry_),
@@ -333,11 +218,9 @@ def test___call___and_execute_success(self, sleep):
         target.assert_called_once_with("meep")
         sleep.assert_not_called()
 
-    # Make uniform return half of its maximum, which is the calculated sleep time.
-    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n / 2.0)
+    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n)
     @mock.patch("time.sleep", autospec=True)
     def test___call___and_execute_retry(self, sleep, uniform):
-
         on_error = mock.Mock(spec=["__call__"], side_effect=[None])
         retry_ = retry.Retry(predicate=retry.if_exception_type(ValueError))
 
@@ -356,24 +239,19 @@ def test___call___and_execute_retry(self, sleep, uniform):
         sleep.assert_called_once_with(retry_._initial)
         assert on_error.call_count == 1
 
-    # Make uniform return half of its maximum, which is the calculated sleep time.
-    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n / 2.0)
+    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n)
     @mock.patch("time.sleep", autospec=True)
-    def test___call___and_execute_retry_hitting_deadline(self, sleep, uniform):
-
+    def test___call___and_execute_retry_hitting_timeout(self, sleep, uniform):
         on_error = mock.Mock(spec=["__call__"], side_effect=[None] * 10)
         retry_ = retry.Retry(
             predicate=retry.if_exception_type(ValueError),
             initial=1.0,
             maximum=1024.0,
             multiplier=2.0,
-            deadline=9.9,
+            timeout=30.9,
         )
 
-        utcnow = datetime.datetime.utcnow()
-        utcnow_patcher = mock.patch(
-            "google.api_core.datetime_helpers.utcnow", return_value=utcnow
-        )
+        monotonic_patcher = mock.patch("time.monotonic", return_value=0)
 
         target = mock.Mock(spec=["__call__"], side_effect=[ValueError()] * 10)
         # __name__ is needed by functools.partial.
@@ -382,11 +260,11 @@ def test___call___and_execute_retry_hitting_deadline(self, sleep, uniform):
         decorated = retry_(target, on_error=on_error)
         target.assert_not_called()
 
-        with utcnow_patcher as patched_utcnow:
+        with monotonic_patcher as patched_monotonic:
             # Make sure that calls to fake time.sleep() also advance the mocked
             # time clock.
             def increase_time(sleep_delay):
-                patched_utcnow.return_value += datetime.timedelta(seconds=sleep_delay)
+                patched_monotonic.return_value += sleep_delay
 
             sleep.side_effect = increase_time
 
@@ -402,8 +280,17 @@ def increase_time(sleep_delay):
         last_wait = sleep.call_args.args[0]
         total_wait = sum(call_args.args[0] for call_args in sleep.call_args_list)
 
-        assert last_wait == 2.9  # and not 8.0, because the last delay was shortened
-        assert total_wait == 9.9  # the same as the deadline
+        assert last_wait == 8.0
+        # Next attempt would be scheduled in 16 secs, 15 + 16 = 31 > 30.9, thus
+        # we do not even wait for it to be scheduled (30.9 is configured timeout).
+        # This changes the previous logic of shortening the last attempt to fit
+        # in the timeout. The previous logic was removed to make Python retry
+        # logic consistent with the other languages and to not disrupt the
+        # randomized retry delays distribution by artificially increasing a
+        # probability of scheduling two (instead of one) last attempts with very
+        # short delay between them, while the second retry having very low chance
+        # of succeeding anyways.
+        assert total_wait == 15.0
 
     @mock.patch("time.sleep", autospec=True)
     def test___init___without_retry_executed(self, sleep):
@@ -428,8 +315,7 @@ def test___init___without_retry_executed(self, sleep):
         sleep.assert_not_called()
         _some_function.assert_not_called()
 
-    # Make uniform return half of its maximum, which is the calculated sleep time.
-    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n / 2.0)
+    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n)
     @mock.patch("time.sleep", autospec=True)
     def test___init___when_retry_is_executed(self, sleep, uniform):
         _some_function = mock.Mock()
diff --git a/tests/unit/test_bidi.py b/tests/unit/test_bidi.py
index b876d9ad..0e7b018c 100644
--- a/tests/unit/test_bidi.py
+++ b/tests/unit/test_bidi.py
@@ -16,11 +16,21 @@
 import logging
 import queue
 import threading
+import time
+
+try:
+    from unittest import mock
+    from unittest.mock import AsyncMock  # pragma: NO COVER  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    import mock  # type: ignore
 
-import grpc
-import mock
 import pytest
 
+try:
+    import grpc
+except ImportError:  # pragma: NO COVER
+    pytest.skip("No GRPC", allow_module_level=True)
+
 from google.api_core import bidi
 from google.api_core import exceptions
 
@@ -287,6 +297,9 @@ def test_close(self):
         # ensure the request queue was signaled to stop.
         assert bidi_rpc.pending_requests == 1
         assert bidi_rpc._request_queue.get() is None
+        # ensure request and callbacks are cleaned up
+        assert bidi_rpc._initial_request is None
+        assert not bidi_rpc._callbacks
 
     def test_close_no_rpc(self):
         bidi_rpc = bidi.BidiRpc(None)
@@ -614,6 +627,8 @@ def cancel_side_effect():
         assert bidi_rpc.pending_requests == 1
         assert bidi_rpc._request_queue.get() is None
         assert bidi_rpc._finalized
+        assert bidi_rpc._initial_request is None
+        assert not bidi_rpc._callbacks
 
     def test_reopen_failure_on_rpc_restart(self):
         error1 = ValueError("1")
@@ -768,6 +783,7 @@ def on_response(response):
         consumer.stop()
 
         assert consumer.is_active is False
+        assert consumer._on_response is None
 
     def test_wake_on_error(self):
         should_continue = threading.Event()
@@ -800,6 +816,21 @@ def test_wake_on_error(self):
         while consumer.is_active:
             pass
 
+    def test_rpc_callback_fires_when_consumer_start_fails(self):
+        expected_exception = exceptions.InvalidArgument(
+            "test", response=grpc.StatusCode.INVALID_ARGUMENT
+        )
+        callback = mock.Mock(spec=["__call__"])
+
+        rpc, _ = make_rpc()
+        bidi_rpc = bidi.BidiRpc(rpc)
+        bidi_rpc.add_done_callback(callback)
+        bidi_rpc._start_rpc.side_effect = expected_exception
+
+        consumer = bidi.BackgroundConsumer(bidi_rpc, on_response=None)
+        consumer.start()
+        assert callback.call_args.args[0] == grpc.StatusCode.INVALID_ARGUMENT
+
     def test_consumer_expected_error(self, caplog):
         caplog.set_level(logging.DEBUG)
 
@@ -836,7 +867,7 @@ def test_consumer_unexpected_error(self, caplog):
 
         # Wait for the consumer's thread to exit.
         while consumer.is_active:
-            pass
+            pass  # pragma: NO COVER (race condition)
 
         on_response.assert_not_called()
         bidi_rpc.recv.assert_called_once()
@@ -860,6 +891,30 @@ def close_side_effect():
 
         consumer.stop()
         assert consumer.is_active is False
+        assert consumer._on_response is None
 
         # calling stop twice should not result in an error.
         consumer.stop()
+
+    def test_stop_error_logs(self, caplog):
+        """
+        Closing the client should result in no internal error logs
+
+        https://github.com/googleapis/python-api-core/issues/788
+        """
+        caplog.set_level(logging.DEBUG)
+        bidi_rpc = mock.create_autospec(bidi.BidiRpc, instance=True)
+        bidi_rpc.is_active = True
+        on_response = mock.Mock(spec=["__call__"])
+
+        consumer = bidi.BackgroundConsumer(bidi_rpc, on_response)
+
+        consumer.start()
+        consumer.stop()
+        # let the background thread run for a while before exiting
+        time.sleep(0.1)
+        bidi_rpc.is_active = False
+        # running thread should not result in error logs
+        error_logs = [r.message for r in caplog.records if r.levelname == "ERROR"]
+        assert not error_logs, f"Found unexpected ERROR logs: {error_logs}"
+        bidi_rpc.is_active = False
diff --git a/tests/unit/test_client_info.py b/tests/unit/test_client_info.py
index f2274ec2..3361fef6 100644
--- a/tests/unit/test_client_info.py
+++ b/tests/unit/test_client_info.py
@@ -13,6 +13,11 @@
 # limitations under the License.
 
 
+try:
+    import grpc
+except ImportError:  # pragma: NO COVER
+    grpc = None
+
 from google.api_core import client_info
 
 
@@ -20,7 +25,12 @@ def test_constructor_defaults():
     info = client_info.ClientInfo()
 
     assert info.python_version is not None
-    assert info.grpc_version is not None
+
+    if grpc is not None:  # pragma: NO COVER
+        assert info.grpc_version is not None
+    else:  # pragma: NO COVER
+        assert info.grpc_version is None
+
     assert info.api_core_version is not None
     assert info.gapic_version is None
     assert info.client_library_version is None
diff --git a/tests/unit/test_client_logging.py b/tests/unit/test_client_logging.py
new file mode 100644
index 00000000..b3b0b5c8
--- /dev/null
+++ b/tests/unit/test_client_logging.py
@@ -0,0 +1,140 @@
+import json
+import logging
+from unittest import mock
+
+from google.api_core.client_logging import (
+    setup_logging,
+    initialize_logging,
+    StructuredLogFormatter,
+)
+
+
+def reset_logger(scope):
+    logger = logging.getLogger(scope)
+    logger.handlers = []
+    logger.setLevel(logging.NOTSET)
+    logger.propagate = True
+
+
+def test_setup_logging_w_no_scopes():
+    with mock.patch("google.api_core.client_logging._BASE_LOGGER_NAME", "foogle"):
+        setup_logging()
+        base_logger = logging.getLogger("foogle")
+        assert base_logger.handlers == []
+        assert not base_logger.propagate
+        assert base_logger.level == logging.NOTSET
+
+    reset_logger("foogle")
+
+
+def test_setup_logging_w_base_scope():
+    with mock.patch("google.api_core.client_logging._BASE_LOGGER_NAME", "foogle"):
+        setup_logging("foogle")
+        base_logger = logging.getLogger("foogle")
+        assert isinstance(base_logger.handlers[0], logging.StreamHandler)
+        assert not base_logger.propagate
+        assert base_logger.level == logging.DEBUG
+
+    reset_logger("foogle")
+
+
+def test_setup_logging_w_configured_scope():
+    with mock.patch("google.api_core.client_logging._BASE_LOGGER_NAME", "foogle"):
+        base_logger = logging.getLogger("foogle")
+        base_logger.propagate = False
+        setup_logging("foogle")
+        assert base_logger.handlers == []
+        assert not base_logger.propagate
+        assert base_logger.level == logging.NOTSET
+
+    reset_logger("foogle")
+
+
+def test_setup_logging_w_module_scope():
+    with mock.patch("google.api_core.client_logging._BASE_LOGGER_NAME", "foogle"):
+        setup_logging("foogle.bar")
+
+        base_logger = logging.getLogger("foogle")
+        assert base_logger.handlers == []
+        assert not base_logger.propagate
+        assert base_logger.level == logging.NOTSET
+
+        module_logger = logging.getLogger("foogle.bar")
+        assert isinstance(module_logger.handlers[0], logging.StreamHandler)
+        assert not module_logger.propagate
+        assert module_logger.level == logging.DEBUG
+
+    reset_logger("foogle")
+    reset_logger("foogle.bar")
+
+
+def test_setup_logging_w_incorrect_scope():
+    with mock.patch("google.api_core.client_logging._BASE_LOGGER_NAME", "foogle"):
+        setup_logging("abc")
+
+        base_logger = logging.getLogger("foogle")
+        assert base_logger.handlers == []
+        assert not base_logger.propagate
+        assert base_logger.level == logging.NOTSET
+
+        # TODO(https://github.com/googleapis/python-api-core/issues/759): update test once we add logic to ignore an incorrect scope.
+        logger = logging.getLogger("abc")
+        assert isinstance(logger.handlers[0], logging.StreamHandler)
+        assert not logger.propagate
+        assert logger.level == logging.DEBUG
+
+    reset_logger("foogle")
+    reset_logger("abc")
+
+
+def test_initialize_logging():
+
+    with mock.patch("os.getenv", return_value="foogle.bar"):
+        with mock.patch("google.api_core.client_logging._BASE_LOGGER_NAME", "foogle"):
+            initialize_logging()
+
+            base_logger = logging.getLogger("foogle")
+            assert base_logger.handlers == []
+            assert not base_logger.propagate
+            assert base_logger.level == logging.NOTSET
+
+            module_logger = logging.getLogger("foogle.bar")
+            assert isinstance(module_logger.handlers[0], logging.StreamHandler)
+            assert not module_logger.propagate
+            assert module_logger.level == logging.DEBUG
+
+            # Check that `initialize_logging()` is a no-op after the first time by verifying that user-set configs are not modified:
+            base_logger.propagate = True
+            module_logger.propagate = True
+
+            initialize_logging()
+
+            assert base_logger.propagate
+            assert module_logger.propagate
+
+    reset_logger("foogle")
+    reset_logger("foogle.bar")
+
+
+def test_structured_log_formatter():
+    # TODO(https://github.com/googleapis/python-api-core/issues/761): Test additional fields when implemented.
+    record = logging.LogRecord(
+        name="Appelation",
+        level=logging.DEBUG,
+        msg="This is a test message.",
+        pathname="some/path",
+        lineno=25,
+        args=None,
+        exc_info=None,
+    )
+
+    # Extra fields:
+    record.rpcName = "bar"
+
+    formatted_msg = StructuredLogFormatter().format(record)
+    parsed_msg = json.loads(formatted_msg)
+
+    assert parsed_msg["name"] == "Appelation"
+    assert parsed_msg["severity"] == "DEBUG"
+    assert parsed_msg["message"] == "This is a test message."
+    assert parsed_msg["rpcName"] == "bar"
diff --git a/tests/unit/test_client_options.py b/tests/unit/test_client_options.py
index 38b9ad0a..396d6627 100644
--- a/tests/unit/test_client_options.py
+++ b/tests/unit/test_client_options.py
@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from re import match
 import pytest
 
 from google.api_core import client_options
@@ -36,6 +37,8 @@ def test_constructor():
             "https://www.googleapis.com/auth/cloud-platform",
             "https://www.googleapis.com/auth/cloud-platform.read-only",
         ],
+        api_audience="foo2.googleapis.com",
+        universe_domain="googleapis.com",
     )
 
     assert options.api_endpoint == "foo.googleapis.com"
@@ -46,6 +49,8 @@ def test_constructor():
         "https://www.googleapis.com/auth/cloud-platform",
         "https://www.googleapis.com/auth/cloud-platform.read-only",
     ]
+    assert options.api_audience == "foo2.googleapis.com"
+    assert options.universe_domain == "googleapis.com"
 
 
 def test_constructor_with_encrypted_cert_source():
@@ -72,10 +77,42 @@ def test_constructor_with_both_cert_sources():
         )
 
 
+def test_constructor_with_api_key():
+
+    options = client_options.ClientOptions(
+        api_endpoint="foo.googleapis.com",
+        client_cert_source=get_client_cert,
+        quota_project_id="quote-proj",
+        api_key="api-key",
+        scopes=[
+            "https://www.googleapis.com/auth/cloud-platform",
+            "https://www.googleapis.com/auth/cloud-platform.read-only",
+        ],
+    )
+
+    assert options.api_endpoint == "foo.googleapis.com"
+    assert options.client_cert_source() == (b"cert", b"key")
+    assert options.quota_project_id == "quote-proj"
+    assert options.api_key == "api-key"
+    assert options.scopes == [
+        "https://www.googleapis.com/auth/cloud-platform",
+        "https://www.googleapis.com/auth/cloud-platform.read-only",
+    ]
+
+
+def test_constructor_with_both_api_key_and_credentials_file():
+    with pytest.raises(ValueError):
+        client_options.ClientOptions(
+            api_key="api-key",
+            credentials_file="path/to/credentials.json",
+        )
+
+
 def test_from_dict():
     options = client_options.from_dict(
         {
             "api_endpoint": "foo.googleapis.com",
+            "universe_domain": "googleapis.com",
             "client_cert_source": get_client_cert,
             "quota_project_id": "quote-proj",
             "credentials_file": "path/to/credentials.json",
@@ -83,10 +120,12 @@ def test_from_dict():
                 "https://www.googleapis.com/auth/cloud-platform",
                 "https://www.googleapis.com/auth/cloud-platform.read-only",
             ],
+            "api_audience": "foo2.googleapis.com",
         }
     )
 
     assert options.api_endpoint == "foo.googleapis.com"
+    assert options.universe_domain == "googleapis.com"
     assert options.client_cert_source() == (b"cert", b"key")
     assert options.quota_project_id == "quote-proj"
     assert options.credentials_file == "path/to/credentials.json"
@@ -94,6 +133,8 @@ def test_from_dict():
         "https://www.googleapis.com/auth/cloud-platform",
         "https://www.googleapis.com/auth/cloud-platform.read-only",
     ]
+    assert options.api_key is None
+    assert options.api_audience == "foo2.googleapis.com"
 
 
 def test_from_dict_bad_argument():
@@ -108,10 +149,22 @@ def test_from_dict_bad_argument():
 
 
 def test_repr():
-    options = client_options.ClientOptions(api_endpoint="foo.googleapis.com")
-
-    assert (
-        repr(options)
-        == "ClientOptions: {'api_endpoint': 'foo.googleapis.com', 'client_cert_source': None, 'client_encrypted_cert_source': None}"
-        or "ClientOptions: {'client_encrypted_cert_source': None, 'client_cert_source': None, 'api_endpoint': 'foo.googleapis.com'}"
+    expected_keys = set(
+        [
+            "api_endpoint",
+            "universe_domain",
+            "client_cert_source",
+            "client_encrypted_cert_source",
+            "quota_project_id",
+            "credentials_file",
+            "scopes",
+            "api_key",
+            "api_audience",
+        ]
     )
+    options = client_options.ClientOptions(api_endpoint="foo.googleapis.com")
+    options_repr = repr(options)
+    options_keys = vars(options).keys()
+    assert match(r"ClientOptions:", options_repr)
+    assert match(r".*'api_endpoint': 'foo.googleapis.com'.*", options_repr)
+    assert options_keys == expected_keys
diff --git a/tests/unit/test_exceptions.py b/tests/unit/test_exceptions.py
index 10599457..e3f8f909 100644
--- a/tests/unit/test_exceptions.py
+++ b/tests/unit/test_exceptions.py
@@ -14,12 +14,20 @@
 
 import http.client
 import json
+from unittest import mock
 
-import grpc
-import mock
+import pytest
 import requests
 
+try:
+    import grpc
+    from grpc_status import rpc_status
+except ImportError:  # pragma: NO COVER
+    grpc = rpc_status = None
+
 from google.api_core import exceptions
+from google.protobuf import any_pb2, json_format
+from google.rpc import error_details_pb2, status_pb2
 
 
 def test_create_google_cloud_error():
@@ -33,11 +41,8 @@ def test_create_google_cloud_error():
 
 def test_create_google_cloud_error_with_args():
     error = {
-        "domain": "global",
-        "location": "test",
-        "locationType": "testing",
+        "code": 600,
         "message": "Testing",
-        "reason": "test",
     }
     response = mock.sentinel.response
     exception = exceptions.GoogleAPICallError("Testing", [error], response=response)
@@ -102,6 +107,7 @@ def test_from_http_response_no_content():
 
 def test_from_http_response_text_content():
     response = make_response(b"message")
+    response.encoding = "UTF8"  # suppress charset_normalizer warning
 
     exception = exceptions.from_http_response(response)
 
@@ -150,6 +156,7 @@ def test_from_http_response_json_unicode_content():
     assert exception.errors == ["1", "2"]
 
 
+@pytest.mark.skipif(grpc is None, reason="No grpc")
 def test_from_grpc_status():
     message = "message"
     exception = exceptions.from_grpc_status(grpc.StatusCode.OUT_OF_RANGE, message)
@@ -161,6 +168,7 @@ def test_from_grpc_status():
     assert exception.errors == []
 
 
+@pytest.mark.skipif(grpc is None, reason="No grpc")
 def test_from_grpc_status_as_int():
     message = "message"
     exception = exceptions.from_grpc_status(11, message)
@@ -172,6 +180,7 @@ def test_from_grpc_status_as_int():
     assert exception.errors == []
 
 
+@pytest.mark.skipif(grpc is None, reason="No grpc")
 def test_from_grpc_status_with_errors_and_response():
     message = "message"
     response = mock.sentinel.response
@@ -186,6 +195,7 @@ def test_from_grpc_status_with_errors_and_response():
     assert exception.response == response
 
 
+@pytest.mark.skipif(grpc is None, reason="No grpc")
 def test_from_grpc_status_unknown_code():
     message = "message"
     exception = exceptions.from_grpc_status(grpc.StatusCode.OK, message)
@@ -193,6 +203,7 @@ def test_from_grpc_status_unknown_code():
     assert exception.message == message
 
 
+@pytest.mark.skipif(grpc is None, reason="No grpc")
 def test_from_grpc_error():
     message = "message"
     error = mock.create_autospec(grpc.Call, instance=True)
@@ -210,6 +221,7 @@ def test_from_grpc_error():
     assert exception.response == error
 
 
+@pytest.mark.skipif(grpc is None, reason="No grpc")
 def test_from_grpc_error_non_call():
     message = "message"
     error = mock.create_autospec(grpc.RpcError, instance=True)
@@ -223,3 +235,161 @@ def test_from_grpc_error_non_call():
     assert exception.message == message
     assert exception.errors == [error]
     assert exception.response == error
+
+
+@pytest.mark.skipif(grpc is None, reason="No grpc")
+def test_from_grpc_error_bare_call():
+    message = "Testing"
+
+    class TestingError(grpc.Call, grpc.RpcError):
+        def __init__(self, exception):
+            self.exception = exception
+
+        def code(self):
+            return self.exception.grpc_status_code
+
+        def details(self):
+            return message
+
+    nested_message = "message"
+    error = TestingError(exceptions.GoogleAPICallError(nested_message))
+
+    exception = exceptions.from_grpc_error(error)
+
+    assert isinstance(exception, exceptions.GoogleAPICallError)
+    assert exception.code is None
+    assert exception.grpc_status_code is None
+    assert exception.message == message
+    assert exception.errors == [error]
+    assert exception.response == error
+    assert exception.details == []
+
+
+def create_bad_request_details():
+    bad_request_details = error_details_pb2.BadRequest()
+    field_violation = bad_request_details.field_violations.add()
+    field_violation.field = "document.content"
+    field_violation.description = "Must have some text content to annotate."
+    status_detail = any_pb2.Any()
+    status_detail.Pack(bad_request_details)
+    return status_detail
+
+
+def create_error_info_details():
+    info = error_details_pb2.ErrorInfo(
+        reason="SERVICE_DISABLED",
+        domain="googleapis.com",
+        metadata={
+            "consumer": "projects/455411330361",
+            "service": "translate.googleapis.com",
+        },
+    )
+    status_detail = any_pb2.Any()
+    status_detail.Pack(info)
+    return status_detail
+
+
+def test_error_details_from_rest_response():
+    bad_request_detail = create_bad_request_details()
+    error_info_detail = create_error_info_details()
+    status = status_pb2.Status()
+    status.code = 3
+    status.message = (
+        "3 INVALID_ARGUMENT: One of content, or gcs_content_uri must be set."
+    )
+    status.details.append(bad_request_detail)
+    status.details.append(error_info_detail)
+
+    # See JSON schema in https://cloud.google.com/apis/design/errors#http_mapping
+    http_response = make_response(
+        json.dumps(
+            {"error": json.loads(json_format.MessageToJson(status, sort_keys=True))}
+        ).encode("utf-8")
+    )
+    exception = exceptions.from_http_response(http_response)
+    want_error_details = [
+        json.loads(json_format.MessageToJson(bad_request_detail)),
+        json.loads(json_format.MessageToJson(error_info_detail)),
+    ]
+    assert want_error_details == exception.details
+
+    # 404 POST comes from make_response.
+    assert str(exception) == (
+        "404 POST https://example.com/: 3 INVALID_ARGUMENT:"
+        " One of content, or gcs_content_uri must be set."
+        " [{'@type': 'type.googleapis.com/google.rpc.BadRequest',"
+        " 'fieldViolations': [{'description': 'Must have some text content to annotate.',"
+        " 'field': 'document.content'}]},"
+        " {'@type': 'type.googleapis.com/google.rpc.ErrorInfo',"
+        " 'domain': 'googleapis.com',"
+        " 'metadata': {'consumer': 'projects/455411330361',"
+        " 'service': 'translate.googleapis.com'},"
+        " 'reason': 'SERVICE_DISABLED'}]"
+    )
+
+
+def test_error_details_from_v1_rest_response():
+    response = make_response(
+        json.dumps(
+            {"error": {"message": "\u2019 message", "errors": ["1", "2"]}}
+        ).encode("utf-8")
+    )
+    exception = exceptions.from_http_response(response)
+    assert exception.details == []
+    assert (
+        exception.reason is None
+        and exception.domain is None
+        and exception.metadata is None
+    )
+
+
+@pytest.mark.skipif(grpc is None, reason="gRPC not importable")
+def test_error_details_from_grpc_response():
+    status = rpc_status.status_pb2.Status()
+    status.code = 3
+    status.message = (
+        "3 INVALID_ARGUMENT: One of content, or gcs_content_uri must be set."
+    )
+    status_br_detail = create_bad_request_details()
+    status_ei_detail = create_error_info_details()
+    status.details.append(status_br_detail)
+    status.details.append(status_ei_detail)
+
+    # The actual error doesn't matter as long as its grpc.Call,
+    # because from_call is mocked.
+    error = mock.create_autospec(grpc.Call, instance=True)
+    with mock.patch("grpc_status.rpc_status.from_call") as m:
+        m.return_value = status
+        exception = exceptions.from_grpc_error(error)
+
+    bad_request_detail = error_details_pb2.BadRequest()
+    error_info_detail = error_details_pb2.ErrorInfo()
+    status_br_detail.Unpack(bad_request_detail)
+    status_ei_detail.Unpack(error_info_detail)
+    assert exception.details == [bad_request_detail, error_info_detail]
+    assert exception.reason == error_info_detail.reason
+    assert exception.domain == error_info_detail.domain
+    assert exception.metadata == error_info_detail.metadata
+
+
+@pytest.mark.skipif(grpc is None, reason="gRPC not importable")
+def test_error_details_from_grpc_response_unknown_error():
+    status_detail = any_pb2.Any()
+
+    status = rpc_status.status_pb2.Status()
+    status.code = 3
+    status.message = (
+        "3 INVALID_ARGUMENT: One of content, or gcs_content_uri must be set."
+    )
+    status.details.append(status_detail)
+
+    error = mock.create_autospec(grpc.Call, instance=True)
+    with mock.patch("grpc_status.rpc_status.from_call") as m:
+        m.return_value = status
+        exception = exceptions.from_grpc_error(error)
+    assert exception.details == [status_detail]
+    assert (
+        exception.reason is None
+        and exception.domain is None
+        and exception.metadata is None
+    )
diff --git a/tests/unit/test_extended_operation.py b/tests/unit/test_extended_operation.py
new file mode 100644
index 00000000..ab550662
--- /dev/null
+++ b/tests/unit/test_extended_operation.py
@@ -0,0 +1,246 @@
+# Copyright 2022 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import dataclasses
+import enum
+import typing
+from unittest import mock
+
+import pytest
+
+from google.api_core import exceptions
+from google.api_core import extended_operation
+from google.api_core import retry
+
+TEST_OPERATION_NAME = "test/extended_operation"
+
+
+@dataclasses.dataclass(frozen=True)
+class CustomOperation:
+    class StatusCode(enum.Enum):
+        UNKNOWN = 0
+        DONE = 1
+        PENDING = 2
+
+    class LROCustomErrors:
+        class LROCustomError:
+            def __init__(self, code: str = "", message: str = ""):
+                self.code = code
+                self.message = message
+
+        def __init__(self, errors: typing.List[LROCustomError] = []):
+            self.errors = errors
+
+    name: str
+    status: StatusCode
+    error_code: typing.Optional[int] = None
+    error_message: typing.Optional[str] = None
+    armor_class: typing.Optional[int] = None
+    # Note: `error` can be removed once proposal A from
+    # b/284179390 is implemented.
+    error: typing.Optional[LROCustomErrors] = None
+
+    # Note: in generated clients, this property must be generated for each
+    # extended operation message type.
+    # The status may be an enum, a string, or a bool. If it's a string or enum,
+    # its text is compared to the string "DONE".
+    @property
+    def done(self):
+        return self.status.name == "DONE"
+
+
+def make_extended_operation(responses=None):
+    client_operations_responses = responses or [
+        CustomOperation(
+            name=TEST_OPERATION_NAME, status=CustomOperation.StatusCode.PENDING
+        )
+    ]
+
+    refresh = mock.Mock(spec=["__call__"], side_effect=client_operations_responses)
+    refresh.responses = client_operations_responses
+    cancel = mock.Mock(spec=["__call__"])
+    extended_operation_future = extended_operation.ExtendedOperation.make(
+        refresh,
+        cancel,
+        client_operations_responses[0],
+    )
+
+    return extended_operation_future, refresh, cancel
+
+
+def test_constructor():
+    ex_op, refresh, _ = make_extended_operation()
+    assert ex_op._extended_operation == refresh.responses[0]
+    assert not ex_op.cancelled()
+    assert not ex_op.done()
+    assert ex_op.name == TEST_OPERATION_NAME
+    assert ex_op.status == CustomOperation.StatusCode.PENDING
+    assert ex_op.error_code is None
+    assert ex_op.error_message is None
+
+
+def test_done():
+    responses = [
+        CustomOperation(
+            name=TEST_OPERATION_NAME, status=CustomOperation.StatusCode.PENDING
+        ),
+        # Second response indicates that the operation has finished.
+        CustomOperation(
+            name=TEST_OPERATION_NAME, status=CustomOperation.StatusCode.DONE
+        ),
+        # Bumper to make sure we stop polling on DONE.
+        CustomOperation(
+            name=TEST_OPERATION_NAME,
+            status=CustomOperation.StatusCode.DONE,
+            error_message="Gone too far!",
+        ),
+    ]
+    ex_op, refresh, _ = make_extended_operation(responses)
+
+    # Start out not done.
+    assert not ex_op.done()
+    assert refresh.call_count == 1
+
+    # Refresh brings us to the done state.
+    assert ex_op.done()
+    assert refresh.call_count == 2
+    assert not ex_op.error_message
+
+    # Make sure that subsequent checks are no-ops.
+    assert ex_op.done()
+    assert refresh.call_count == 2
+    assert not ex_op.error_message
+
+
+def test_cancellation():
+    responses = [
+        CustomOperation(
+            name=TEST_OPERATION_NAME, status=CustomOperation.StatusCode.PENDING
+        ),
+        # Second response indicates that the operation was cancelled.
+        CustomOperation(
+            name=TEST_OPERATION_NAME, status=CustomOperation.StatusCode.DONE
+        ),
+    ]
+    ex_op, _, cancel = make_extended_operation(responses)
+
+    assert not ex_op.cancelled()
+
+    assert ex_op.cancel()
+    assert ex_op.cancelled()
+    cancel.assert_called_once_with()
+
+    # Cancelling twice should have no effect.
+    assert not ex_op.cancel()
+    cancel.assert_called_once_with()
+
+
+def test_done_w_retry():
+    # Not sure what's going on here with the coverage, so just ignore it.
+    test_retry = retry.Retry(predicate=lambda x: True)  # pragma: NO COVER
+
+    responses = [
+        CustomOperation(
+            name=TEST_OPERATION_NAME, status=CustomOperation.StatusCode.PENDING
+        ),
+        CustomOperation(
+            name=TEST_OPERATION_NAME, status=CustomOperation.StatusCode.DONE
+        ),
+    ]
+
+    ex_op, refresh, _ = make_extended_operation(responses)
+
+    ex_op.done(retry=test_retry)
+
+    refresh.assert_called_once_with(retry=test_retry)
+
+
+def test_error():
+    responses = [
+        CustomOperation(
+            name=TEST_OPERATION_NAME,
+            status=CustomOperation.StatusCode.DONE,
+            error_code=400,
+            error_message="Bad request",
+        ),
+    ]
+
+    ex_op, _, _ = make_extended_operation(responses)
+
+    # Defaults to CallError when grpc is not installed
+    with pytest.raises(exceptions.BadRequest):
+        ex_op.result()
+
+    # Test GCE custom LRO Error. See b/284179390
+    # Note: This test case can be removed once proposal A from
+    # b/284179390 is implemented.
+    _EXCEPTION_CODE = "INCOMPATIBLE_BACKEND_SERVICES"
+    _EXCEPTION_MESSAGE = "Validation failed for instance group"
+    responses = [
+        CustomOperation(
+            name=TEST_OPERATION_NAME,
+            status=CustomOperation.StatusCode.DONE,
+            error_code=400,
+            error_message="Bad request",
+            error=CustomOperation.LROCustomErrors(
+                errors=[
+                    CustomOperation.LROCustomErrors.LROCustomError(
+                        code=_EXCEPTION_CODE, message=_EXCEPTION_MESSAGE
+                    )
+                ]
+            ),
+        ),
+    ]
+
+    ex_op, _, _ = make_extended_operation(responses)
+
+    # Defaults to CallError when grpc is not installed
+    with pytest.raises(
+        exceptions.BadRequest, match=f"{_EXCEPTION_CODE}: {_EXCEPTION_MESSAGE}"
+    ):
+        ex_op.result()
+
+    # Inconsistent result
+    responses = [
+        CustomOperation(
+            name=TEST_OPERATION_NAME,
+            status=CustomOperation.StatusCode.DONE,
+            error_code=2112,
+        ),
+    ]
+
+    ex_op, _, _ = make_extended_operation(responses)
+
+    with pytest.raises(exceptions.GoogleAPICallError):
+        ex_op.result()
+
+
+def test_pass_through():
+    responses = [
+        CustomOperation(
+            name=TEST_OPERATION_NAME,
+            status=CustomOperation.StatusCode.PENDING,
+            armor_class=10,
+        ),
+        CustomOperation(
+            name=TEST_OPERATION_NAME,
+            status=CustomOperation.StatusCode.DONE,
+            armor_class=20,
+        ),
+    ]
+    ex_op, _, _ = make_extended_operation(responses)
+
+    assert ex_op.armor_class == 10
+    ex_op.result()
+    assert ex_op.armor_class == 20
diff --git a/tests/unit/test_grpc_helpers.py b/tests/unit/test_grpc_helpers.py
index 12bf1849..8de9d8c0 100644
--- a/tests/unit/test_grpc_helpers.py
+++ b/tests/unit/test_grpc_helpers.py
@@ -12,10 +12,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import grpc
-import mock
+from unittest import mock
+
 import pytest
 
+try:
+    import grpc
+except ImportError:  # pragma: NO COVER
+    pytest.skip("No GRPC", allow_module_level=True)
+
 from google.api_core import exceptions
 from google.api_core import grpc_helpers
 import google.auth.credentials
@@ -52,6 +57,9 @@ def code(self):
     def details(self):
         return None
 
+    def trailing_metadata(self):
+        return None
+
 
 def test_wrap_unary_errors():
     grpc_error = RpcErrorImpl(grpc.StatusCode.INVALID_ARGUMENT)
@@ -66,6 +74,145 @@ def test_wrap_unary_errors():
     assert exc_info.value.response == grpc_error
 
 
+class Test_StreamingResponseIterator:
+    @staticmethod
+    def _make_wrapped(*items):
+        return iter(items)
+
+    @staticmethod
+    def _make_one(wrapped, **kw):
+        return grpc_helpers._StreamingResponseIterator(wrapped, **kw)
+
+    def test_ctor_defaults(self):
+        wrapped = self._make_wrapped("a", "b", "c")
+        iterator = self._make_one(wrapped)
+        assert iterator._stored_first_result == "a"
+        assert list(wrapped) == ["b", "c"]
+
+    def test_ctor_explicit(self):
+        wrapped = self._make_wrapped("a", "b", "c")
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+        assert getattr(iterator, "_stored_first_result", self) is self
+        assert list(wrapped) == ["a", "b", "c"]
+
+    def test_ctor_w_rpc_error_on_prefetch(self):
+        wrapped = mock.MagicMock()
+        wrapped.__next__.side_effect = grpc.RpcError()
+
+        with pytest.raises(grpc.RpcError):
+            self._make_one(wrapped)
+
+    def test___iter__(self):
+        wrapped = self._make_wrapped("a", "b", "c")
+        iterator = self._make_one(wrapped)
+        assert iter(iterator) is iterator
+
+    def test___next___w_cached_first_result(self):
+        wrapped = self._make_wrapped("a", "b", "c")
+        iterator = self._make_one(wrapped)
+        assert next(iterator) == "a"
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+        assert next(iterator) == "b"
+        assert next(iterator) == "c"
+
+    def test___next___wo_cached_first_result(self):
+        wrapped = self._make_wrapped("a", "b", "c")
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+        assert next(iterator) == "a"
+        assert next(iterator) == "b"
+        assert next(iterator) == "c"
+
+    def test___next___w_rpc_error(self):
+        wrapped = mock.MagicMock()
+        wrapped.__next__.side_effect = grpc.RpcError()
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+
+        with pytest.raises(exceptions.GoogleAPICallError):
+            next(iterator)
+
+    def test_add_callback(self):
+        wrapped = mock.MagicMock()
+        callback = mock.Mock(spec={})
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+
+        assert iterator.add_callback(callback) is wrapped.add_callback.return_value
+
+        wrapped.add_callback.assert_called_once_with(callback)
+
+    def test_cancel(self):
+        wrapped = mock.MagicMock()
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+
+        assert iterator.cancel() is wrapped.cancel.return_value
+
+        wrapped.cancel.assert_called_once_with()
+
+    def test_code(self):
+        wrapped = mock.MagicMock()
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+
+        assert iterator.code() is wrapped.code.return_value
+
+        wrapped.code.assert_called_once_with()
+
+    def test_details(self):
+        wrapped = mock.MagicMock()
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+
+        assert iterator.details() is wrapped.details.return_value
+
+        wrapped.details.assert_called_once_with()
+
+    def test_initial_metadata(self):
+        wrapped = mock.MagicMock()
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+
+        assert iterator.initial_metadata() is wrapped.initial_metadata.return_value
+
+        wrapped.initial_metadata.assert_called_once_with()
+
+    def test_is_active(self):
+        wrapped = mock.MagicMock()
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+
+        assert iterator.is_active() is wrapped.is_active.return_value
+
+        wrapped.is_active.assert_called_once_with()
+
+    def test_time_remaining(self):
+        wrapped = mock.MagicMock()
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+
+        assert iterator.time_remaining() is wrapped.time_remaining.return_value
+
+        wrapped.time_remaining.assert_called_once_with()
+
+    def test_trailing_metadata(self):
+        wrapped = mock.MagicMock()
+        iterator = self._make_one(wrapped, prefetch_first_result=False)
+
+        assert iterator.trailing_metadata() is wrapped.trailing_metadata.return_value
+
+        wrapped.trailing_metadata.assert_called_once_with()
+
+
+class TestGrpcStream(Test_StreamingResponseIterator):
+    @staticmethod
+    def _make_one(wrapped, **kw):
+        return grpc_helpers.GrpcStream(wrapped, **kw)
+
+    def test_grpc_stream_attributes(self):
+        """
+        Should be both a grpc.Call and an iterable
+        """
+        call = self._make_one(None)
+        assert isinstance(call, grpc.Call)
+        # should implement __iter__
+        assert hasattr(call, "__iter__")
+        it = call.__iter__()
+        assert hasattr(it, "__next__")
+
+
 def test_wrap_stream_okay():
     expected_responses = [1, 2, 3]
     callable_ = mock.Mock(spec=["__call__"], return_value=iter(expected_responses))
@@ -93,7 +240,7 @@ def test_wrap_stream_prefetch_disabled():
     callable_.assert_called_once_with(1, 2, three="four")
 
 
-def test_wrap_stream_iterable_iterface():
+def test_wrap_stream_iterable_interface():
     response_iter = mock.create_autospec(grpc.Call, instance=True)
     callable_ = mock.Mock(spec=["__call__"], return_value=response_iter)
 
@@ -219,36 +366,72 @@ def test_wrap_errors_streaming(wrap_stream_errors):
     wrap_stream_errors.assert_called_once_with(callable_)
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@pytest.mark.parametrize(
+    "attempt_direct_path,target,expected_target",
+    [
+        (None, "example.com:443", "example.com:443"),
+        (False, "example.com:443", "example.com:443"),
+        (True, "example.com:443", "google-c2p:///example.com"),
+        (True, "dns:///example.com", "google-c2p:///example.com"),
+        (True, "another-c2p:///example.com", "another-c2p:///example.com"),
+    ],
+)
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch(
     "google.auth.default",
     autospec=True,
-    return_value=(mock.sentinel.credentials, mock.sentinel.projet),
+    return_value=(mock.sentinel.credentials, mock.sentinel.project),
 )
 @mock.patch("grpc.secure_channel")
-def test_create_channel_implicit(grpc_secure_channel, default, composite_creds_call):
-    target = "example.com:443"
+def test_create_channel_implicit(
+    grpc_secure_channel,
+    google_auth_default,
+    composite_creds_call,
+    attempt_direct_path,
+    target,
+    expected_target,
+):
     composite_creds = composite_creds_call.return_value
 
-    channel = grpc_helpers.create_channel(target)
+    channel = grpc_helpers.create_channel(
+        target,
+        compression=grpc.Compression.Gzip,
+        attempt_direct_path=attempt_direct_path,
+    )
 
     assert channel is grpc_secure_channel.return_value
 
-    default.assert_called_once_with(scopes=None, default_scopes=None)
+    google_auth_default.assert_called_once_with(scopes=None, default_scopes=None)
 
-    if grpc_helpers.HAS_GRPC_GCP:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
+        # The original target is the expected target
+        expected_target = target
+        grpc_secure_channel.assert_called_once_with(
+            expected_target, composite_creds, None
+        )
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            expected_target, composite_creds, compression=grpc.Compression.Gzip
+        )
 
 
+@pytest.mark.parametrize(
+    "attempt_direct_path,target, expected_target",
+    [
+        (None, "example.com:443", "example.com:443"),
+        (False, "example.com:443", "example.com:443"),
+        (True, "example.com:443", "google-c2p:///example.com"),
+        (True, "dns:///example.com", "google-c2p:///example.com"),
+        (True, "another-c2p:///example.com", "another-c2p:///example.com"),
+    ],
+)
 @mock.patch("google.auth.transport.grpc.AuthMetadataPlugin", autospec=True)
 @mock.patch(
     "google.auth.transport.requests.Request",
     autospec=True,
     return_value=mock.sentinel.Request,
 )
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch(
     "google.auth.default",
     autospec=True,
@@ -256,58 +439,95 @@ def test_create_channel_implicit(grpc_secure_channel, default, composite_creds_c
 )
 @mock.patch("grpc.secure_channel")
 def test_create_channel_implicit_with_default_host(
-    grpc_secure_channel, default, composite_creds_call, request, auth_metadata_plugin
+    grpc_secure_channel,
+    google_auth_default,
+    composite_creds_call,
+    request,
+    auth_metadata_plugin,
+    attempt_direct_path,
+    target,
+    expected_target,
 ):
-    target = "example.com:443"
     default_host = "example.com"
     composite_creds = composite_creds_call.return_value
 
-    channel = grpc_helpers.create_channel(target, default_host=default_host)
+    channel = grpc_helpers.create_channel(
+        target, default_host=default_host, attempt_direct_path=attempt_direct_path
+    )
 
     assert channel is grpc_secure_channel.return_value
 
-    default.assert_called_once_with(scopes=None, default_scopes=None)
+    google_auth_default.assert_called_once_with(scopes=None, default_scopes=None)
     auth_metadata_plugin.assert_called_once_with(
         mock.sentinel.credentials, mock.sentinel.Request, default_host=default_host
     )
 
-    if grpc_helpers.HAS_GRPC_GCP:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
+        # The original target is the expected target
+        expected_target = target
+        grpc_secure_channel.assert_called_once_with(
+            expected_target, composite_creds, None
+        )
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            expected_target, composite_creds, compression=None
+        )
 
 
+@pytest.mark.parametrize(
+    "attempt_direct_path",
+    [
+        None,
+        False,
+    ],
+)
 @mock.patch("grpc.composite_channel_credentials")
 @mock.patch(
     "google.auth.default",
     autospec=True,
-    return_value=(mock.sentinel.credentials, mock.sentinel.projet),
+    return_value=(mock.sentinel.credentials, mock.sentinel.project),
 )
 @mock.patch("grpc.secure_channel")
 def test_create_channel_implicit_with_ssl_creds(
-    grpc_secure_channel, default, composite_creds_call
+    grpc_secure_channel, default, composite_creds_call, attempt_direct_path
 ):
     target = "example.com:443"
 
     ssl_creds = grpc.ssl_channel_credentials()
 
-    grpc_helpers.create_channel(target, ssl_credentials=ssl_creds)
+    grpc_helpers.create_channel(
+        target, ssl_credentials=ssl_creds, attempt_direct_path=attempt_direct_path
+    )
 
     default.assert_called_once_with(scopes=None, default_scopes=None)
 
     composite_creds_call.assert_called_once_with(ssl_creds, mock.ANY)
     composite_creds = composite_creds_call.return_value
-    if grpc_helpers.HAS_GRPC_GCP:
+
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
         grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            target, composite_creds, compression=None
+        )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+def test_create_channel_implicit_with_ssl_creds_attempt_direct_path_true():
+    target = "example.com:443"
+    ssl_creds = grpc.ssl_channel_credentials()
+    with pytest.raises(
+        ValueError, match="Using ssl_credentials with Direct Path is not supported"
+    ):
+        grpc_helpers.create_channel(
+            target, ssl_credentials=ssl_creds, attempt_direct_path=True
+        )
+
+
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch(
     "google.auth.default",
     autospec=True,
-    return_value=(mock.sentinel.credentials, mock.sentinel.projet),
+    return_value=(mock.sentinel.credentials, mock.sentinel.project),
 )
 @mock.patch("grpc.secure_channel")
 def test_create_channel_implicit_with_scopes(
@@ -322,17 +542,19 @@ def test_create_channel_implicit_with_scopes(
 
     default.assert_called_once_with(scopes=["one", "two"], default_scopes=None)
 
-    if grpc_helpers.HAS_GRPC_GCP:
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
         grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            target, composite_creds, compression=None
+        )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch(
     "google.auth.default",
     autospec=True,
-    return_value=(mock.sentinel.credentials, mock.sentinel.projet),
+    return_value=(mock.sentinel.credentials, mock.sentinel.project),
 )
 @mock.patch("grpc.secure_channel")
 def test_create_channel_implicit_with_default_scopes(
@@ -347,10 +569,12 @@ def test_create_channel_implicit_with_default_scopes(
 
     default.assert_called_once_with(scopes=None, default_scopes=["three", "four"])
 
-    if grpc_helpers.HAS_GRPC_GCP:
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
         grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            target, composite_creds, compression=None
+        )
 
 
 def test_create_channel_explicit_with_duplicate_credentials():
@@ -364,7 +588,7 @@ def test_create_channel_explicit_with_duplicate_credentials():
         )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch("google.auth.credentials.with_scopes_if_required", autospec=True)
 @mock.patch("grpc.secure_channel")
 def test_create_channel_explicit(grpc_secure_channel, auth_creds, composite_creds_call):
@@ -378,13 +602,16 @@ def test_create_channel_explicit(grpc_secure_channel, auth_creds, composite_cred
     )
 
     assert channel is grpc_secure_channel.return_value
-    if grpc_helpers.HAS_GRPC_GCP:
+
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
         grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            target, composite_creds, compression=None
+        )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch("grpc.secure_channel")
 def test_create_channel_explicit_scoped(grpc_secure_channel, composite_creds_call):
     target = "example.com:443"
@@ -401,13 +628,16 @@ def test_create_channel_explicit_scoped(grpc_secure_channel, composite_creds_cal
     credentials.with_scopes.assert_called_once_with(scopes, default_scopes=None)
 
     assert channel is grpc_secure_channel.return_value
-    if grpc_helpers.HAS_GRPC_GCP:
+
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
         grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            target, composite_creds, compression=None
+        )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch("grpc.secure_channel")
 def test_create_channel_explicit_default_scopes(
     grpc_secure_channel, composite_creds_call
@@ -428,13 +658,16 @@ def test_create_channel_explicit_default_scopes(
     )
 
     assert channel is grpc_secure_channel.return_value
-    if grpc_helpers.HAS_GRPC_GCP:
+
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
         grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            target, composite_creds, compression=None
+        )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch("grpc.secure_channel")
 def test_create_channel_explicit_with_quota_project(
     grpc_secure_channel, composite_creds_call
@@ -453,13 +686,16 @@ def test_create_channel_explicit_with_quota_project(
     credentials.with_quota_project.assert_called_once_with("project-foo")
 
     assert channel is grpc_secure_channel.return_value
-    if grpc_helpers.HAS_GRPC_GCP:
+
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
         grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            target, composite_creds, compression=None
+        )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch("grpc.secure_channel")
 @mock.patch(
     "google.auth.load_credentials_from_file",
@@ -481,13 +717,16 @@ def test_create_channel_with_credentials_file(
     )
 
     assert channel is grpc_secure_channel.return_value
-    if grpc_helpers.HAS_GRPC_GCP:
+
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
         grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            target, composite_creds, compression=None
+        )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch("grpc.secure_channel")
 @mock.patch(
     "google.auth.load_credentials_from_file",
@@ -512,13 +751,16 @@ def test_create_channel_with_credentials_file_and_scopes(
     )
 
     assert channel is grpc_secure_channel.return_value
-    if grpc_helpers.HAS_GRPC_GCP:
+
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
         grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            target, composite_creds, compression=None
+        )
 
 
-@mock.patch("grpc.composite_channel_credentials")
+@mock.patch("grpc.compute_engine_channel_credentials")
 @mock.patch("grpc.secure_channel")
 @mock.patch(
     "google.auth.load_credentials_from_file",
@@ -543,17 +785,20 @@ def test_create_channel_with_credentials_file_and_default_scopes(
     )
 
     assert channel is grpc_secure_channel.return_value
-    if grpc_helpers.HAS_GRPC_GCP:
+
+    if grpc_helpers.HAS_GRPC_GCP:  # pragma: NO COVER
         grpc_secure_channel.assert_called_once_with(target, composite_creds, None)
     else:
-        grpc_secure_channel.assert_called_once_with(target, composite_creds)
+        grpc_secure_channel.assert_called_once_with(
+            target, composite_creds, compression=None
+        )
 
 
 @pytest.mark.skipif(
     not grpc_helpers.HAS_GRPC_GCP, reason="grpc_gcp module not available"
 )
 @mock.patch("grpc_gcp.secure_channel")
-def test_create_channel_with_grpc_gcp(grpc_gcp_secure_channel):
+def test_create_channel_with_grpc_gcp(grpc_gcp_secure_channel):  # pragma: NO COVER
     target = "example.com:443"
     scopes = ["test_scope"]
 
@@ -676,6 +921,7 @@ def test_call_info(self):
         stub = operations_pb2.OperationsStub(channel)
         expected_request = operations_pb2.GetOperationRequest(name="meep")
         expected_response = operations_pb2.Operation(name="moop")
+        expected_compression = grpc.Compression.NoCompression
         expected_metadata = [("red", "blue"), ("two", "shoe")]
         expected_credentials = mock.sentinel.credentials
         channel.GetOperation.response = expected_response
@@ -683,6 +929,7 @@ def test_call_info(self):
         response = stub.GetOperation(
             expected_request,
             timeout=42,
+            compression=expected_compression,
             metadata=expected_metadata,
             credentials=expected_credentials,
         )
@@ -690,7 +937,13 @@ def test_call_info(self):
         assert response == expected_response
         assert channel.requests == [("GetOperation", expected_request)]
         assert channel.GetOperation.calls == [
-            (expected_request, 42, expected_metadata, expected_credentials)
+            (
+                expected_request,
+                42,
+                expected_metadata,
+                expected_credentials,
+                expected_compression,
+            )
         ]
 
     def test_unary_unary(self):
diff --git a/tests/unit/test_iam.py b/tests/unit/test_iam.py
index fbd242e5..3de15288 100644
--- a/tests/unit/test_iam.py
+++ b/tests/unit/test_iam.py
@@ -167,14 +167,15 @@ def test_owners_getter(self):
         assert policy.owners == expected
 
     def test_owners_setter(self):
-        import warnings
         from google.api_core.iam import OWNER_ROLE
 
         MEMBER = "user:phred@example.com"
         expected = set([MEMBER])
         policy = self._make_one()
 
-        with warnings.catch_warnings(record=True) as warned:
+        with pytest.warns(
+            DeprecationWarning, match="Assigning to 'owners' is deprecated."
+        ) as warned:
             policy.owners = [MEMBER]
 
         (warning,) = warned
@@ -191,14 +192,15 @@ def test_editors_getter(self):
         assert policy.editors == expected
 
     def test_editors_setter(self):
-        import warnings
         from google.api_core.iam import EDITOR_ROLE
 
         MEMBER = "user:phred@example.com"
         expected = set([MEMBER])
         policy = self._make_one()
 
-        with warnings.catch_warnings(record=True) as warned:
+        with pytest.warns(
+            DeprecationWarning, match="Assigning to 'editors' is deprecated."
+        ) as warned:
             policy.editors = [MEMBER]
 
         (warning,) = warned
@@ -215,14 +217,15 @@ def test_viewers_getter(self):
         assert policy.viewers == expected
 
     def test_viewers_setter(self):
-        import warnings
         from google.api_core.iam import VIEWER_ROLE
 
         MEMBER = "user:phred@example.com"
         expected = set([MEMBER])
         policy = self._make_one()
 
-        with warnings.catch_warnings(record=True) as warned:
+        with pytest.warns(
+            DeprecationWarning, match="Assigning to 'viewers' is deprecated."
+        ) as warned:
             policy.viewers = [MEMBER]
 
         (warning,) = warned
@@ -337,12 +340,13 @@ def test_to_api_repr_binding_wo_members(self):
         assert policy.to_api_repr() == {}
 
     def test_to_api_repr_binding_w_duplicates(self):
-        import warnings
         from google.api_core.iam import OWNER_ROLE
 
         OWNER = "group:cloud-logs@google.com"
         policy = self._make_one()
-        with warnings.catch_warnings(record=True):
+        with pytest.warns(
+            DeprecationWarning, match="Assigning to 'owners' is deprecated."
+        ):
             policy.owners = [OWNER, OWNER]
         assert policy.to_api_repr() == {
             "bindings": [{"role": OWNER_ROLE, "members": [OWNER]}]
diff --git a/tests/unit/test_operation.py b/tests/unit/test_operation.py
index 28fbfe27..80680720 100644
--- a/tests/unit/test_operation.py
+++ b/tests/unit/test_operation.py
@@ -13,7 +13,14 @@
 # limitations under the License.
 
 
-import mock
+from unittest import mock
+
+import pytest
+
+try:
+    import grpc  # noqa: F401
+except ImportError:  # pragma: NO COVER
+    pytest.skip("No GRPC", allow_module_level=True)
 
 from google.api_core import exceptions
 from google.api_core import operation
diff --git a/tests/unit/test_packaging.py b/tests/unit/test_packaging.py
new file mode 100644
index 00000000..8100a496
--- /dev/null
+++ b/tests/unit/test_packaging.py
@@ -0,0 +1,28 @@
+# Copyright 2023 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+import subprocess
+import sys
+
+
+def test_namespace_package_compat(tmp_path):
+    # The ``google`` namespace package should not be masked
+    # by the presence of ``google-api-core``.
+    google = tmp_path / "google"
+    google.mkdir()
+    google.joinpath("othermod.py").write_text("")
+    env = dict(os.environ, PYTHONPATH=str(tmp_path))
+    cmd = [sys.executable, "-m", "google.othermod"]
+    subprocess.check_call(cmd, env=env)
diff --git a/tests/unit/test_page_iterator.py b/tests/unit/test_page_iterator.py
index a44e998b..560722c5 100644
--- a/tests/unit/test_page_iterator.py
+++ b/tests/unit/test_page_iterator.py
@@ -14,8 +14,8 @@
 
 import math
 import types
+from unittest import mock
 
-import mock
 import pytest
 
 from google.api_core import page_iterator
@@ -505,7 +505,8 @@ def api_request(*args, **kw):
                 assert list(next(items_iter)) == [
                     dict(name=str(i))
                     for i in range(
-                        ipage * page_size, min((ipage + 1) * page_size, n_results),
+                        ipage * page_size,
+                        min((ipage + 1) * page_size, n_results),
                     )
                 ]
         else:
diff --git a/tests/unit/test_path_template.py b/tests/unit/test_path_template.py
index 4c8a7c5e..c34dd0f3 100644
--- a/tests/unit/test_path_template.py
+++ b/tests/unit/test_path_template.py
@@ -13,10 +13,11 @@
 # limitations under the License.
 
 from __future__ import unicode_literals
+from unittest import mock
 
-import mock
 import pytest
 
+from google.api import auth_pb2
 from google.api_core import path_template
 
 
@@ -84,6 +85,61 @@ def test_expanded_failure(tmpl, args, kwargs, exc_match):
         path_template.expand(tmpl, *args, **kwargs)
 
 
+@pytest.mark.parametrize(
+    "request_obj, field, expected_result",
+    [
+        [{"field": "stringValue"}, "field", "stringValue"],
+        [{"field": "stringValue"}, "nosuchfield", None],
+        [{"field": "stringValue"}, "field.subfield", None],
+        [{"field": {"subfield": "stringValue"}}, "field", None],
+        [{"field": {"subfield": "stringValue"}}, "field.subfield", "stringValue"],
+        [{"field": {"subfield": [1, 2, 3]}}, "field.subfield", [1, 2, 3]],
+        [{"field": {"subfield": "stringValue"}}, "field", None],
+        [{"field": {"subfield": "stringValue"}}, "field.nosuchfield", None],
+        [
+            {"field": {"subfield": {"subsubfield": "stringValue"}}},
+            "field.subfield.subsubfield",
+            "stringValue",
+        ],
+        ["string", "field", None],
+    ],
+)
+def test_get_field(request_obj, field, expected_result):
+    result = path_template.get_field(request_obj, field)
+    assert result == expected_result
+
+
+@pytest.mark.parametrize(
+    "request_obj, field, expected_result",
+    [
+        [{"field": "stringValue"}, "field", {}],
+        [{"field": "stringValue"}, "nosuchfield", {"field": "stringValue"}],
+        [{"field": "stringValue"}, "field.subfield", {"field": "stringValue"}],
+        [{"field": {"subfield": "stringValue"}}, "field.subfield", {"field": {}}],
+        [
+            {"field": {"subfield": "stringValue", "q": "w"}, "e": "f"},
+            "field.subfield",
+            {"field": {"q": "w"}, "e": "f"},
+        ],
+        [
+            {"field": {"subfield": "stringValue"}},
+            "field.nosuchfield",
+            {"field": {"subfield": "stringValue"}},
+        ],
+        [
+            {"field": {"subfield": {"subsubfield": "stringValue", "q": "w"}}},
+            "field.subfield.subsubfield",
+            {"field": {"subfield": {"q": "w"}}},
+        ],
+        ["string", "field", "string"],
+        ["string", "field.subfield", "string"],
+    ],
+)
+def test_delete_field(request_obj, field, expected_result):
+    path_template.delete_field(request_obj, field)
+    assert request_obj == expected_result
+
+
 @pytest.mark.parametrize(
     "tmpl, path",
     [
@@ -113,3 +169,484 @@ def test__replace_variable_with_pattern():
     match.group.return_value = None
     with pytest.raises(ValueError, match="Unknown"):
         path_template._replace_variable_with_pattern(match)
+
+
+@pytest.mark.parametrize(
+    "http_options, message, request_kwargs, expected_result",
+    [
+        [
+            [["get", "/v1/no/template", ""]],
+            None,
+            {"foo": "bar"},
+            ["get", "/v1/no/template", {}, {"foo": "bar"}],
+        ],
+        [
+            [["get", "/v1/no/template", ""]],
+            auth_pb2.AuthenticationRule(selector="bar"),
+            {},
+            [
+                "get",
+                "/v1/no/template",
+                None,
+                auth_pb2.AuthenticationRule(selector="bar"),
+            ],
+        ],
+        # Single templates
+        [
+            [["get", "/v1/{field}", ""]],
+            None,
+            {"field": "parent"},
+            ["get", "/v1/parent", {}, {}],
+        ],
+        [
+            [["get", "/v1/{selector}", ""]],
+            auth_pb2.AuthenticationRule(selector="parent"),
+            {},
+            ["get", "/v1/parent", None, auth_pb2.AuthenticationRule()],
+        ],
+        [
+            [["get", "/v1/{field.sub}", ""]],
+            None,
+            {"field": {"sub": "parent"}, "foo": "bar"},
+            ["get", "/v1/parent", {}, {"field": {}, "foo": "bar"}],
+        ],
+        [
+            [["get", "/v1/{oauth.canonical_scopes}", ""]],
+            auth_pb2.AuthenticationRule(
+                selector="bar",
+                oauth=auth_pb2.OAuthRequirements(canonical_scopes="parent"),
+            ),
+            {},
+            [
+                "get",
+                "/v1/parent",
+                None,
+                auth_pb2.AuthenticationRule(
+                    selector="bar", oauth=auth_pb2.OAuthRequirements()
+                ),
+            ],
+        ],
+    ],
+)
+def test_transcode_base_case(http_options, message, request_kwargs, expected_result):
+    http_options, expected_result = helper_test_transcode(http_options, expected_result)
+    result = path_template.transcode(http_options, message, **request_kwargs)
+    assert result == expected_result
+
+
+@pytest.mark.parametrize(
+    "http_options, message, request_kwargs, expected_result",
+    [
+        [
+            [["get", "/v1/{field.subfield}", ""]],
+            None,
+            {"field": {"subfield": "parent"}, "foo": "bar"},
+            ["get", "/v1/parent", {}, {"field": {}, "foo": "bar"}],
+        ],
+        [
+            [["get", "/v1/{oauth.canonical_scopes}", ""]],
+            auth_pb2.AuthenticationRule(
+                selector="bar",
+                oauth=auth_pb2.OAuthRequirements(canonical_scopes="parent"),
+            ),
+            {},
+            [
+                "get",
+                "/v1/parent",
+                None,
+                auth_pb2.AuthenticationRule(
+                    selector="bar", oauth=auth_pb2.OAuthRequirements()
+                ),
+            ],
+        ],
+        [
+            [["get", "/v1/{field.subfield.subsubfield}", ""]],
+            None,
+            {"field": {"subfield": {"subsubfield": "parent"}}, "foo": "bar"},
+            ["get", "/v1/parent", {}, {"field": {"subfield": {}}, "foo": "bar"}],
+        ],
+        [
+            [["get", "/v1/{field.subfield1}/{field.subfield2}", ""]],
+            None,
+            {"field": {"subfield1": "parent", "subfield2": "child"}, "foo": "bar"},
+            ["get", "/v1/parent/child", {}, {"field": {}, "foo": "bar"}],
+        ],
+        [
+            [["get", "/v1/{selector}/{oauth.canonical_scopes}", ""]],
+            auth_pb2.AuthenticationRule(
+                selector="parent",
+                oauth=auth_pb2.OAuthRequirements(canonical_scopes="child"),
+            ),
+            {"field": {"subfield1": "parent", "subfield2": "child"}, "foo": "bar"},
+            [
+                "get",
+                "/v1/parent/child",
+                None,
+                auth_pb2.AuthenticationRule(oauth=auth_pb2.OAuthRequirements()),
+            ],
+        ],
+    ],
+)
+def test_transcode_subfields(http_options, message, request_kwargs, expected_result):
+    http_options, expected_result = helper_test_transcode(http_options, expected_result)
+    result = path_template.transcode(http_options, message, **request_kwargs)
+    assert result == expected_result
+
+
+@pytest.mark.parametrize(
+    "http_options, message, request_kwargs, expected_result",
+    [
+        # Single segment wildcard
+        [
+            [["get", "/v1/{field=*}", ""]],
+            None,
+            {"field": "parent"},
+            ["get", "/v1/parent", {}, {}],
+        ],
+        [
+            [["get", "/v1/{selector=*}", ""]],
+            auth_pb2.AuthenticationRule(selector="parent"),
+            {},
+            ["get", "/v1/parent", None, auth_pb2.AuthenticationRule()],
+        ],
+        [
+            [["get", "/v1/{field=a/*/b/*}", ""]],
+            None,
+            {"field": "a/parent/b/child", "foo": "bar"},
+            ["get", "/v1/a/parent/b/child", {}, {"foo": "bar"}],
+        ],
+        [
+            [["get", "/v1/{selector=a/*/b/*}", ""]],
+            auth_pb2.AuthenticationRule(
+                selector="a/parent/b/child", allow_without_credential=True
+            ),
+            {},
+            [
+                "get",
+                "/v1/a/parent/b/child",
+                None,
+                auth_pb2.AuthenticationRule(allow_without_credential=True),
+            ],
+        ],
+        # Double segment wildcard
+        [
+            [["get", "/v1/{field=**}", ""]],
+            None,
+            {"field": "parent/p1"},
+            ["get", "/v1/parent/p1", {}, {}],
+        ],
+        [
+            [["get", "/v1/{selector=**}", ""]],
+            auth_pb2.AuthenticationRule(selector="parent/p1"),
+            {},
+            ["get", "/v1/parent/p1", None, auth_pb2.AuthenticationRule()],
+        ],
+        [
+            [["get", "/v1/{field=a/**/b/**}", ""]],
+            None,
+            {"field": "a/parent/p1/b/child/c1", "foo": "bar"},
+            ["get", "/v1/a/parent/p1/b/child/c1", {}, {"foo": "bar"}],
+        ],
+        [
+            [["get", "/v1/{selector=a/**/b/**}", ""]],
+            auth_pb2.AuthenticationRule(
+                selector="a/parent/p1/b/child/c1", allow_without_credential=True
+            ),
+            {},
+            [
+                "get",
+                "/v1/a/parent/p1/b/child/c1",
+                None,
+                auth_pb2.AuthenticationRule(allow_without_credential=True),
+            ],
+        ],
+        # Combined single and double segment wildcard
+        [
+            [["get", "/v1/{field=a/*/b/**}", ""]],
+            None,
+            {"field": "a/parent/b/child/c1"},
+            ["get", "/v1/a/parent/b/child/c1", {}, {}],
+        ],
+        [
+            [["get", "/v1/{selector=a/*/b/**}", ""]],
+            auth_pb2.AuthenticationRule(selector="a/parent/b/child/c1"),
+            {},
+            ["get", "/v1/a/parent/b/child/c1", None, auth_pb2.AuthenticationRule()],
+        ],
+        [
+            [["get", "/v1/{field=a/**/b/*}/v2/{name}", ""]],
+            None,
+            {"field": "a/parent/p1/b/child", "name": "first", "foo": "bar"},
+            ["get", "/v1/a/parent/p1/b/child/v2/first", {}, {"foo": "bar"}],
+        ],
+        [
+            [["get", "/v1/{selector=a/**/b/*}/v2/{oauth.canonical_scopes}", ""]],
+            auth_pb2.AuthenticationRule(
+                selector="a/parent/p1/b/child",
+                oauth=auth_pb2.OAuthRequirements(canonical_scopes="first"),
+            ),
+            {"field": "a/parent/p1/b/child", "name": "first", "foo": "bar"},
+            [
+                "get",
+                "/v1/a/parent/p1/b/child/v2/first",
+                None,
+                auth_pb2.AuthenticationRule(oauth=auth_pb2.OAuthRequirements()),
+            ],
+        ],
+    ],
+)
+def test_transcode_with_wildcard(
+    http_options, message, request_kwargs, expected_result
+):
+    http_options, expected_result = helper_test_transcode(http_options, expected_result)
+    result = path_template.transcode(http_options, message, **request_kwargs)
+    assert result == expected_result
+
+
+@pytest.mark.parametrize(
+    "http_options, message, request_kwargs, expected_result",
+    [
+        # Single field body
+        [
+            [["post", "/v1/no/template", "data"]],
+            None,
+            {"data": {"id": 1, "info": "some info"}, "foo": "bar"},
+            ["post", "/v1/no/template", {"id": 1, "info": "some info"}, {"foo": "bar"}],
+        ],
+        [
+            [["post", "/v1/no/template", "oauth"]],
+            auth_pb2.AuthenticationRule(
+                selector="bar",
+                oauth=auth_pb2.OAuthRequirements(canonical_scopes="child"),
+            ),
+            {},
+            [
+                "post",
+                "/v1/no/template",
+                auth_pb2.OAuthRequirements(canonical_scopes="child"),
+                auth_pb2.AuthenticationRule(selector="bar"),
+            ],
+        ],
+        [
+            [["post", "/v1/{field=a/*}/b/{name=**}", "data"]],
+            None,
+            {
+                "field": "a/parent",
+                "name": "first/last",
+                "data": {"id": 1, "info": "some info"},
+                "foo": "bar",
+            },
+            [
+                "post",
+                "/v1/a/parent/b/first/last",
+                {"id": 1, "info": "some info"},
+                {"foo": "bar"},
+            ],
+        ],
+        [
+            [["post", "/v1/{selector=a/*}/b/{oauth.canonical_scopes=**}", "oauth"]],
+            auth_pb2.AuthenticationRule(
+                selector="a/parent",
+                allow_without_credential=True,
+                requirements=[auth_pb2.AuthRequirement(provider_id="p")],
+                oauth=auth_pb2.OAuthRequirements(canonical_scopes="first/last"),
+            ),
+            {},
+            [
+                "post",
+                "/v1/a/parent/b/first/last",
+                auth_pb2.OAuthRequirements(),
+                auth_pb2.AuthenticationRule(
+                    requirements=[auth_pb2.AuthRequirement(provider_id="p")],
+                    allow_without_credential=True,
+                ),
+            ],
+        ],
+        # Wildcard body
+        [
+            [["post", "/v1/{field=a/*}/b/{name=**}", "*"]],
+            None,
+            {
+                "field": "a/parent",
+                "name": "first/last",
+                "data": {"id": 1, "info": "some info"},
+                "foo": "bar",
+            },
+            [
+                "post",
+                "/v1/a/parent/b/first/last",
+                {"data": {"id": 1, "info": "some info"}, "foo": "bar"},
+                {},
+            ],
+        ],
+        [
+            [["post", "/v1/{selector=a/*}/b/{oauth.canonical_scopes=**}", "*"]],
+            auth_pb2.AuthenticationRule(
+                selector="a/parent",
+                allow_without_credential=True,
+                oauth=auth_pb2.OAuthRequirements(canonical_scopes="first/last"),
+            ),
+            {
+                "field": "a/parent",
+                "name": "first/last",
+                "data": {"id": 1, "info": "some info"},
+                "foo": "bar",
+            },
+            [
+                "post",
+                "/v1/a/parent/b/first/last",
+                auth_pb2.AuthenticationRule(
+                    allow_without_credential=True, oauth=auth_pb2.OAuthRequirements()
+                ),
+                auth_pb2.AuthenticationRule(),
+            ],
+        ],
+    ],
+)
+def test_transcode_with_body(http_options, message, request_kwargs, expected_result):
+    http_options, expected_result = helper_test_transcode(http_options, expected_result)
+    result = path_template.transcode(http_options, message, **request_kwargs)
+    assert result == expected_result
+
+
+@pytest.mark.parametrize(
+    "http_options, message, request_kwargs, expected_result",
+    [
+        # Additional bindings
+        [
+            [
+                ["post", "/v1/{field=a/*}/b/{name=**}", "extra_data"],
+                ["post", "/v1/{field=a/*}/b/{name=**}", "*"],
+            ],
+            None,
+            {
+                "field": "a/parent",
+                "name": "first/last",
+                "data": {"id": 1, "info": "some info"},
+                "foo": "bar",
+            },
+            [
+                "post",
+                "/v1/a/parent/b/first/last",
+                {"data": {"id": 1, "info": "some info"}, "foo": "bar"},
+                {},
+            ],
+        ],
+        [
+            [
+                [
+                    "post",
+                    "/v1/{selector=a/*}/b/{oauth.canonical_scopes=**}",
+                    "extra_data",
+                ],
+                ["post", "/v1/{selector=a/*}/b/{oauth.canonical_scopes=**}", "*"],
+            ],
+            auth_pb2.AuthenticationRule(
+                selector="a/parent",
+                allow_without_credential=True,
+                oauth=auth_pb2.OAuthRequirements(canonical_scopes="first/last"),
+            ),
+            {},
+            [
+                "post",
+                "/v1/a/parent/b/first/last",
+                auth_pb2.AuthenticationRule(
+                    allow_without_credential=True, oauth=auth_pb2.OAuthRequirements()
+                ),
+                auth_pb2.AuthenticationRule(),
+            ],
+        ],
+        [
+            [
+                ["get", "/v1/{field=a/*}/b/{name=**}", ""],
+                ["get", "/v1/{field=a/*}/b/first/last", ""],
+            ],
+            None,
+            {"field": "a/parent", "foo": "bar"},
+            ["get", "/v1/a/parent/b/first/last", {}, {"foo": "bar"}],
+        ],
+        [
+            [
+                ["get", "/v1/{selector=a/*}/b/{oauth.allow_without_credential=**}", ""],
+                ["get", "/v1/{selector=a/*}/b/first/last", ""],
+            ],
+            auth_pb2.AuthenticationRule(
+                selector="a/parent",
+                allow_without_credential=True,
+                oauth=auth_pb2.OAuthRequirements(),
+            ),
+            {},
+            [
+                "get",
+                "/v1/a/parent/b/first/last",
+                None,
+                auth_pb2.AuthenticationRule(
+                    allow_without_credential=True, oauth=auth_pb2.OAuthRequirements()
+                ),
+            ],
+        ],
+    ],
+)
+def test_transcode_with_additional_bindings(
+    http_options, message, request_kwargs, expected_result
+):
+    http_options, expected_result = helper_test_transcode(http_options, expected_result)
+    result = path_template.transcode(http_options, message, **request_kwargs)
+    assert result == expected_result
+
+
+@pytest.mark.parametrize(
+    "http_options, message, request_kwargs",
+    [
+        [[["get", "/v1/{name}", ""]], None, {"foo": "bar"}],
+        [[["get", "/v1/{selector}", ""]], auth_pb2.AuthenticationRule(), {}],
+        [[["get", "/v1/{name}", ""]], auth_pb2.AuthenticationRule(), {}],
+        [[["get", "/v1/{name}", ""]], None, {"name": "first/last"}],
+        [
+            [["get", "/v1/{selector}", ""]],
+            auth_pb2.AuthenticationRule(selector="first/last"),
+            {},
+        ],
+        [[["get", "/v1/{name=mr/*/*}", ""]], None, {"name": "first/last"}],
+        [
+            [["get", "/v1/{selector=mr/*/*}", ""]],
+            auth_pb2.AuthenticationRule(selector="first/last"),
+            {},
+        ],
+        [[["post", "/v1/{name}", "data"]], None, {"name": "first/last"}],
+        [
+            [["post", "/v1/{selector}", "data"]],
+            auth_pb2.AuthenticationRule(selector="first"),
+            {},
+        ],
+        [[["post", "/v1/{first_name}", "data"]], None, {"last_name": "last"}],
+        [
+            [["post", "/v1/{first_name}", ""]],
+            auth_pb2.AuthenticationRule(selector="first"),
+            {},
+        ],
+    ],
+)
+def test_transcode_fails(http_options, message, request_kwargs):
+    http_options, _ = helper_test_transcode(http_options, range(4))
+    with pytest.raises(ValueError) as exc_info:
+        path_template.transcode(http_options, message, **request_kwargs)
+    assert str(exc_info.value).count("URI") == len(http_options)
+
+
+def helper_test_transcode(http_options_list, expected_result_list):
+    http_options = []
+    for opt_list in http_options_list:
+        http_option = {"method": opt_list[0], "uri": opt_list[1]}
+        if opt_list[2]:
+            http_option["body"] = opt_list[2]
+        http_options.append(http_option)
+
+    expected_result = {
+        "method": expected_result_list[0],
+        "uri": expected_result_list[1],
+        "query_params": expected_result_list[3],
+    }
+    if expected_result_list[2]:
+        expected_result["body"] = expected_result_list[2]
+    return (http_options, expected_result)
diff --git a/tests/unit/test_protobuf_helpers.py b/tests/unit/test_protobuf_helpers.py
index 3df45df5..5678d3bc 100644
--- a/tests/unit/test_protobuf_helpers.py
+++ b/tests/unit/test_protobuf_helpers.py
@@ -12,9 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import sys
-
 import pytest
+import re
 
 from google.api import http_pb2
 from google.api_core import protobuf_helpers
@@ -67,7 +66,12 @@ def test_from_any_pb_failure():
     in_message = any_pb2.Any()
     in_message.Pack(date_pb2.Date(year=1990))
 
-    with pytest.raises(TypeError):
+    with pytest.raises(
+        TypeError,
+        match=re.escape(
+            "Could not convert `google.type.Date` with underlying type `google.protobuf.any_pb2.Any` to `google.type.TimeOfDay`"
+        ),
+    ):
         protobuf_helpers.from_any_pb(timeofday_pb2.TimeOfDay, in_message)
 
 
@@ -476,11 +480,6 @@ def test_field_mask_different_level_diffs():
     ]
 
 
-@pytest.mark.skipif(
-    sys.version_info.major == 2,
-    reason="Field names with trailing underscores can only be created"
-    "through proto-plus, which is Python 3 only.",
-)
 def test_field_mask_ignore_trailing_underscore():
     import proto
 
@@ -496,11 +495,6 @@ class Foo(proto.Message):
     ]
 
 
-@pytest.mark.skipif(
-    sys.version_info.major == 2,
-    reason="Field names with trailing underscores can only be created"
-    "through proto-plus, which is Python 3 only.",
-)
 def test_field_mask_ignore_trailing_underscore_with_nesting():
     import proto
 
diff --git a/tests/unit/test_rest_helpers.py b/tests/unit/test_rest_helpers.py
new file mode 100644
index 00000000..ff1a43f0
--- /dev/null
+++ b/tests/unit/test_rest_helpers.py
@@ -0,0 +1,94 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import pytest
+
+from google.api_core import rest_helpers
+
+
+def test_flatten_simple_value():
+    with pytest.raises(TypeError):
+        rest_helpers.flatten_query_params("abc")
+
+
+def test_flatten_list():
+    with pytest.raises(TypeError):
+        rest_helpers.flatten_query_params(["abc", "def"])
+
+
+def test_flatten_none():
+    assert rest_helpers.flatten_query_params(None) == []
+
+
+def test_flatten_empty_dict():
+    assert rest_helpers.flatten_query_params({}) == []
+
+
+def test_flatten_simple_dict():
+    obj = {"a": "abc", "b": "def", "c": True, "d": False, "e": 10, "f": -3.76}
+    assert rest_helpers.flatten_query_params(obj) == [
+        ("a", "abc"),
+        ("b", "def"),
+        ("c", True),
+        ("d", False),
+        ("e", 10),
+        ("f", -3.76),
+    ]
+
+
+def test_flatten_simple_dict_strict():
+    obj = {"a": "abc", "b": "def", "c": True, "d": False, "e": 10, "f": -3.76}
+    assert rest_helpers.flatten_query_params(obj, strict=True) == [
+        ("a", "abc"),
+        ("b", "def"),
+        ("c", "true"),
+        ("d", "false"),
+        ("e", "10"),
+        ("f", "-3.76"),
+    ]
+
+
+def test_flatten_repeated_field():
+    assert rest_helpers.flatten_query_params({"a": ["x", "y", "z", None]}) == [
+        ("a", "x"),
+        ("a", "y"),
+        ("a", "z"),
+    ]
+
+
+def test_flatten_nested_dict():
+    obj = {"a": {"b": {"c": ["x", "y", "z"]}}, "d": {"e": "uvw"}}
+    expected_result = [("a.b.c", "x"), ("a.b.c", "y"), ("a.b.c", "z"), ("d.e", "uvw")]
+
+    assert rest_helpers.flatten_query_params(obj) == expected_result
+
+
+def test_flatten_repeated_dict():
+    obj = {
+        "a": {"b": {"c": [{"v": 1}, {"v": 2}]}},
+        "d": "uvw",
+    }
+
+    with pytest.raises(ValueError):
+        rest_helpers.flatten_query_params(obj)
+
+
+def test_flatten_repeated_list():
+    obj = {
+        "a": {"b": {"c": [["e", "f"], ["g", "h"]]}},
+        "d": "uvw",
+    }
+
+    with pytest.raises(ValueError):
+        rest_helpers.flatten_query_params(obj)
diff --git a/tests/unit/test_rest_streaming.py b/tests/unit/test_rest_streaming.py
new file mode 100644
index 00000000..0f998dfe
--- /dev/null
+++ b/tests/unit/test_rest_streaming.py
@@ -0,0 +1,296 @@
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import datetime
+import logging
+import random
+import time
+from typing import List
+from unittest.mock import patch
+
+import proto
+import pytest
+import requests
+
+from google.api_core import rest_streaming
+from google.api import http_pb2
+from google.api import httpbody_pb2
+
+from ..helpers import Composer, Song, EchoResponse, parse_responses
+
+
+__protobuf__ = proto.module(package=__name__)
+SEED = int(time.time())
+logging.info(f"Starting sync rest streaming tests with random seed: {SEED}")
+random.seed(SEED)
+
+
+class ResponseMock(requests.Response):
+    class _ResponseItr:
+        def __init__(self, _response_bytes: bytes, random_split=False):
+            self._responses_bytes = _response_bytes
+            self._i = 0
+            self._random_split = random_split
+
+        def __next__(self):
+            if self._i == len(self._responses_bytes):
+                raise StopIteration
+            if self._random_split:
+                n = random.randint(1, len(self._responses_bytes[self._i :]))
+            else:
+                n = 1
+            x = self._responses_bytes[self._i : self._i + n]
+            self._i += n
+            return x.decode("utf-8")
+
+    def __init__(
+        self,
+        responses: List[proto.Message],
+        response_cls,
+        random_split=False,
+    ):
+        super().__init__()
+        self._responses = responses
+        self._random_split = random_split
+        self._response_message_cls = response_cls
+
+    def _parse_responses(self):
+        return parse_responses(self._response_message_cls, self._responses)
+
+    def close(self):
+        raise NotImplementedError()
+
+    def iter_content(self, *args, **kwargs):
+        return self._ResponseItr(
+            self._parse_responses(),
+            random_split=self._random_split,
+        )
+
+
+@pytest.mark.parametrize(
+    "random_split,resp_message_is_proto_plus",
+    [(False, True), (False, False)],
+)
+def test_next_simple(random_split, resp_message_is_proto_plus):
+    if resp_message_is_proto_plus:
+        response_type = EchoResponse
+        responses = [EchoResponse(content="hello world"), EchoResponse(content="yes")]
+    else:
+        response_type = httpbody_pb2.HttpBody
+        responses = [
+            httpbody_pb2.HttpBody(content_type="hello world"),
+            httpbody_pb2.HttpBody(content_type="yes"),
+        ]
+
+    resp = ResponseMock(
+        responses=responses, random_split=random_split, response_cls=response_type
+    )
+    itr = rest_streaming.ResponseIterator(resp, response_type)
+    assert list(itr) == responses
+
+
+@pytest.mark.parametrize(
+    "random_split,resp_message_is_proto_plus",
+    [
+        (True, True),
+        (False, True),
+        (True, False),
+        (False, False),
+    ],
+)
+def test_next_nested(random_split, resp_message_is_proto_plus):
+    if resp_message_is_proto_plus:
+        response_type = Song
+        responses = [
+            Song(title="some song", composer=Composer(given_name="some name")),
+            Song(title="another song", date_added=datetime.datetime(2021, 12, 17)),
+        ]
+    else:
+        # Although `http_pb2.HttpRule`` is used in the response, any response message
+        # can be used which meets this criteria for the test of having a nested field.
+        response_type = http_pb2.HttpRule
+        responses = [
+            http_pb2.HttpRule(
+                selector="some selector",
+                custom=http_pb2.CustomHttpPattern(kind="some kind"),
+            ),
+            http_pb2.HttpRule(
+                selector="another selector",
+                custom=http_pb2.CustomHttpPattern(path="some path"),
+            ),
+        ]
+    resp = ResponseMock(
+        responses=responses, random_split=random_split, response_cls=response_type
+    )
+    itr = rest_streaming.ResponseIterator(resp, response_type)
+    assert list(itr) == responses
+
+
+@pytest.mark.parametrize(
+    "random_split,resp_message_is_proto_plus",
+    [
+        (True, True),
+        (False, True),
+        (True, False),
+        (False, False),
+    ],
+)
+def test_next_stress(random_split, resp_message_is_proto_plus):
+    n = 50
+    if resp_message_is_proto_plus:
+        response_type = Song
+        responses = [
+            Song(title="title_%d" % i, composer=Composer(given_name="name_%d" % i))
+            for i in range(n)
+        ]
+    else:
+        response_type = http_pb2.HttpRule
+        responses = [
+            http_pb2.HttpRule(
+                selector="selector_%d" % i,
+                custom=http_pb2.CustomHttpPattern(path="path_%d" % i),
+            )
+            for i in range(n)
+        ]
+    resp = ResponseMock(
+        responses=responses, random_split=random_split, response_cls=response_type
+    )
+    itr = rest_streaming.ResponseIterator(resp, response_type)
+    assert list(itr) == responses
+
+
+@pytest.mark.parametrize(
+    "random_split,resp_message_is_proto_plus",
+    [
+        (True, True),
+        (False, True),
+        (True, False),
+        (False, False),
+    ],
+)
+def test_next_escaped_characters_in_string(random_split, resp_message_is_proto_plus):
+    if resp_message_is_proto_plus:
+        response_type = Song
+        composer_with_relateds = Composer()
+        relateds = ["Artist A", "Artist B"]
+        composer_with_relateds.relateds = relateds
+
+        responses = [
+            Song(
+                title='ti"tle\nfoo\tbar{}', composer=Composer(given_name="name\n\n\n")
+            ),
+            Song(
+                title='{"this is weird": "totally"}',
+                composer=Composer(given_name="\\{}\\"),
+            ),
+            Song(title='\\{"key": ["value",]}\\', composer=composer_with_relateds),
+        ]
+    else:
+        response_type = http_pb2.Http
+        responses = [
+            http_pb2.Http(
+                rules=[
+                    http_pb2.HttpRule(
+                        selector='ti"tle\nfoo\tbar{}',
+                        custom=http_pb2.CustomHttpPattern(kind="name\n\n\n"),
+                    )
+                ]
+            ),
+            http_pb2.Http(
+                rules=[
+                    http_pb2.HttpRule(
+                        selector='{"this is weird": "totally"}',
+                        custom=http_pb2.CustomHttpPattern(kind="\\{}\\"),
+                    )
+                ]
+            ),
+            http_pb2.Http(
+                rules=[
+                    http_pb2.HttpRule(
+                        selector='\\{"key": ["value",]}\\',
+                        custom=http_pb2.CustomHttpPattern(kind="\\{}\\"),
+                    )
+                ]
+            ),
+        ]
+    resp = ResponseMock(
+        responses=responses, random_split=random_split, response_cls=response_type
+    )
+    itr = rest_streaming.ResponseIterator(resp, response_type)
+    assert list(itr) == responses
+
+
+@pytest.mark.parametrize("response_type", [EchoResponse, httpbody_pb2.HttpBody])
+def test_next_not_array(response_type):
+    with patch.object(
+        ResponseMock, "iter_content", return_value=iter('{"hello": 0}')
+    ) as mock_method:
+        resp = ResponseMock(responses=[], response_cls=response_type)
+        itr = rest_streaming.ResponseIterator(resp, response_type)
+        with pytest.raises(ValueError):
+            next(itr)
+        mock_method.assert_called_once()
+
+
+@pytest.mark.parametrize("response_type", [EchoResponse, httpbody_pb2.HttpBody])
+def test_cancel(response_type):
+    with patch.object(ResponseMock, "close", return_value=None) as mock_method:
+        resp = ResponseMock(responses=[], response_cls=response_type)
+        itr = rest_streaming.ResponseIterator(resp, response_type)
+        itr.cancel()
+        mock_method.assert_called_once()
+
+
+@pytest.mark.parametrize(
+    "response_type,return_value",
+    [
+        (EchoResponse, bytes('[{"content": "hello"}, {', "utf-8")),
+        (httpbody_pb2.HttpBody, bytes('[{"content_type": "hello"}, {', "utf-8")),
+    ],
+)
+def test_check_buffer(response_type, return_value):
+    with patch.object(
+        ResponseMock,
+        "_parse_responses",
+        return_value=return_value,
+    ):
+        resp = ResponseMock(responses=[], response_cls=response_type)
+        itr = rest_streaming.ResponseIterator(resp, response_type)
+        with pytest.raises(ValueError):
+            next(itr)
+            next(itr)
+
+
+@pytest.mark.parametrize("response_type", [EchoResponse, httpbody_pb2.HttpBody])
+def test_next_html(response_type):
+    with patch.object(
+        ResponseMock, "iter_content", return_value=iter("<!DOCTYPE html><html></html>")
+    ) as mock_method:
+        resp = ResponseMock(responses=[], response_cls=response_type)
+        itr = rest_streaming.ResponseIterator(resp, response_type)
+        with pytest.raises(ValueError):
+            next(itr)
+        mock_method.assert_called_once()
+
+
+def test_invalid_response_class():
+    class SomeClass:
+        pass
+
+    resp = ResponseMock(responses=[], response_cls=SomeClass)
+    with pytest.raises(
+        ValueError,
+        match="Response message class must be a subclass of proto.Message or google.protobuf.message.Message",
+    ):
+        rest_streaming.ResponseIterator(resp, SomeClass)
diff --git a/tests/unit/test_timeout.py b/tests/unit/test_timeout.py
index 30d624e2..2c20202b 100644
--- a/tests/unit/test_timeout.py
+++ b/tests/unit/test_timeout.py
@@ -14,14 +14,13 @@
 
 import datetime
 import itertools
+from unittest import mock
 
-import mock
-
-from google.api_core import timeout
+from google.api_core import timeout as timeouts
 
 
 def test__exponential_timeout_generator_base_2():
-    gen = timeout._exponential_timeout_generator(1.0, 60.0, 2.0, deadline=None)
+    gen = timeouts._exponential_timeout_generator(1.0, 60.0, 2.0, deadline=None)
 
     result = list(itertools.islice(gen, 8))
     assert result == [1, 2, 4, 8, 16, 32, 60, 60]
@@ -34,7 +33,7 @@ def test__exponential_timeout_generator_base_deadline(utcnow):
         datetime.datetime.min + datetime.timedelta(seconds=n) for n in range(15)
     ]
 
-    gen = timeout._exponential_timeout_generator(1.0, 60.0, 2.0, deadline=30.0)
+    gen = timeouts._exponential_timeout_generator(1.0, 60.0, 2.0, deadline=30.0)
 
     result = list(itertools.islice(gen, 14))
     # Should grow until the cumulative time is > 30s, then start decreasing as
@@ -42,22 +41,105 @@ def test__exponential_timeout_generator_base_deadline(utcnow):
     assert result == [1, 2, 4, 8, 16, 24, 23, 22, 21, 20, 19, 18, 17, 16]
 
 
+class TestTimeToDeadlineTimeout(object):
+    def test_constructor(self):
+        timeout_ = timeouts.TimeToDeadlineTimeout()
+        assert timeout_._timeout is None
+
+    def test_constructor_args(self):
+        timeout_ = timeouts.TimeToDeadlineTimeout(42.0)
+        assert timeout_._timeout == 42.0
+
+    def test___str__(self):
+        timeout_ = timeouts.TimeToDeadlineTimeout(1)
+        assert str(timeout_) == "<TimeToDeadlineTimeout timeout=1.0>"
+
+    def test_apply(self):
+        target = mock.Mock(spec=["__call__", "__name__"], __name__="target")
+
+        datetime.datetime.now(tz=datetime.timezone.utc)
+        datetime.timedelta(seconds=1)
+
+        now = datetime.datetime.now(tz=datetime.timezone.utc)
+
+        times = [
+            now,
+            now + datetime.timedelta(seconds=0.0009),
+            now + datetime.timedelta(seconds=1),
+            now + datetime.timedelta(seconds=39),
+            now + datetime.timedelta(seconds=42),
+            now + datetime.timedelta(seconds=43),
+        ]
+
+        def _clock():
+            return times.pop(0)
+
+        timeout_ = timeouts.TimeToDeadlineTimeout(42.0, _clock)
+        wrapped = timeout_(target)
+
+        wrapped()
+        target.assert_called_with(timeout=42.0)
+        wrapped()
+        target.assert_called_with(timeout=41.0)
+        wrapped()
+        target.assert_called_with(timeout=3.0)
+        wrapped()
+        target.assert_called_with(timeout=42.0)
+        wrapped()
+        target.assert_called_with(timeout=42.0)
+
+    def test_apply_no_timeout(self):
+        target = mock.Mock(spec=["__call__", "__name__"], __name__="target")
+
+        datetime.datetime.now(tz=datetime.timezone.utc)
+        datetime.timedelta(seconds=1)
+
+        now = datetime.datetime.now(tz=datetime.timezone.utc)
+
+        times = [
+            now,
+            now + datetime.timedelta(seconds=0.0009),
+            now + datetime.timedelta(seconds=1),
+            now + datetime.timedelta(seconds=2),
+        ]
+
+        def _clock():
+            return times.pop(0)
+
+        timeout_ = timeouts.TimeToDeadlineTimeout(clock=_clock)
+        wrapped = timeout_(target)
+
+        wrapped()
+        target.assert_called_with()
+        wrapped()
+        target.assert_called_with()
+
+    def test_apply_passthrough(self):
+        target = mock.Mock(spec=["__call__", "__name__"], __name__="target")
+        timeout_ = timeouts.TimeToDeadlineTimeout(42.0)
+        wrapped = timeout_(target)
+
+        wrapped(1, 2, meep="moop")
+
+        target.assert_called_once_with(1, 2, meep="moop", timeout=42.0)
+
+
 class TestConstantTimeout(object):
     def test_constructor(self):
-        timeout_ = timeout.ConstantTimeout()
+        timeout_ = timeouts.ConstantTimeout()
         assert timeout_._timeout is None
 
     def test_constructor_args(self):
-        timeout_ = timeout.ConstantTimeout(42.0)
+        timeout_ = timeouts.ConstantTimeout(42.0)
         assert timeout_._timeout == 42.0
 
     def test___str__(self):
-        timeout_ = timeout.ConstantTimeout(1)
+        timeout_ = timeouts.ConstantTimeout(1)
         assert str(timeout_) == "<ConstantTimeout timeout=1.0>"
 
     def test_apply(self):
         target = mock.Mock(spec=["__call__", "__name__"], __name__="target")
-        timeout_ = timeout.ConstantTimeout(42.0)
+        timeout_ = timeouts.ConstantTimeout(42.0)
         wrapped = timeout_(target)
 
         wrapped()
@@ -66,7 +148,7 @@ def test_apply(self):
 
     def test_apply_passthrough(self):
         target = mock.Mock(spec=["__call__", "__name__"], __name__="target")
-        timeout_ = timeout.ConstantTimeout(42.0)
+        timeout_ = timeouts.ConstantTimeout(42.0)
         wrapped = timeout_(target)
 
         wrapped(1, 2, meep="moop")
@@ -76,30 +158,30 @@ def test_apply_passthrough(self):
 
 class TestExponentialTimeout(object):
     def test_constructor(self):
-        timeout_ = timeout.ExponentialTimeout()
-        assert timeout_._initial == timeout._DEFAULT_INITIAL_TIMEOUT
-        assert timeout_._maximum == timeout._DEFAULT_MAXIMUM_TIMEOUT
-        assert timeout_._multiplier == timeout._DEFAULT_TIMEOUT_MULTIPLIER
-        assert timeout_._deadline == timeout._DEFAULT_DEADLINE
+        timeout_ = timeouts.ExponentialTimeout()
+        assert timeout_._initial == timeouts._DEFAULT_INITIAL_TIMEOUT
+        assert timeout_._maximum == timeouts._DEFAULT_MAXIMUM_TIMEOUT
+        assert timeout_._multiplier == timeouts._DEFAULT_TIMEOUT_MULTIPLIER
+        assert timeout_._deadline == timeouts._DEFAULT_DEADLINE
 
     def test_constructor_args(self):
-        timeout_ = timeout.ExponentialTimeout(1, 2, 3, 4)
+        timeout_ = timeouts.ExponentialTimeout(1, 2, 3, 4)
         assert timeout_._initial == 1
         assert timeout_._maximum == 2
         assert timeout_._multiplier == 3
         assert timeout_._deadline == 4
 
     def test_with_timeout(self):
-        original_timeout = timeout.ExponentialTimeout()
+        original_timeout = timeouts.ExponentialTimeout()
         timeout_ = original_timeout.with_deadline(42)
         assert original_timeout is not timeout_
-        assert timeout_._initial == timeout._DEFAULT_INITIAL_TIMEOUT
-        assert timeout_._maximum == timeout._DEFAULT_MAXIMUM_TIMEOUT
-        assert timeout_._multiplier == timeout._DEFAULT_TIMEOUT_MULTIPLIER
+        assert timeout_._initial == timeouts._DEFAULT_INITIAL_TIMEOUT
+        assert timeout_._maximum == timeouts._DEFAULT_MAXIMUM_TIMEOUT
+        assert timeout_._multiplier == timeouts._DEFAULT_TIMEOUT_MULTIPLIER
         assert timeout_._deadline == 42
 
     def test___str__(self):
-        timeout_ = timeout.ExponentialTimeout(1, 2, 3, 4)
+        timeout_ = timeouts.ExponentialTimeout(1, 2, 3, 4)
         assert str(timeout_) == (
             "<ExponentialTimeout initial=1.0, maximum=2.0, multiplier=3.0, "
             "deadline=4.0>"
@@ -107,7 +189,7 @@ def test___str__(self):
 
     def test_apply(self):
         target = mock.Mock(spec=["__call__", "__name__"], __name__="target")
-        timeout_ = timeout.ExponentialTimeout(1, 10, 2)
+        timeout_ = timeouts.ExponentialTimeout(1, 10, 2)
         wrapped = timeout_(target)
 
         wrapped()
@@ -121,7 +203,7 @@ def test_apply(self):
 
     def test_apply_passthrough(self):
         target = mock.Mock(spec=["__call__", "__name__"], __name__="target")
-        timeout_ = timeout.ExponentialTimeout(42.0, 100, 2)
+        timeout_ = timeouts.ExponentialTimeout(42.0, 100, 2)
         wrapped = timeout_(target)
 
         wrapped(1, 2, meep="moop")
diff --git a/tests/unit/test_universe.py b/tests/unit/test_universe.py
new file mode 100644
index 00000000..214e00ac
--- /dev/null
+++ b/tests/unit/test_universe.py
@@ -0,0 +1,63 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import pytest
+from google.api_core import universe
+
+
+class _Fake_Credentials:
+    def __init__(self, universe_domain=None):
+        if universe_domain:
+            self.universe_domain = universe_domain
+
+
+def test_determine_domain():
+    domain_client = "foo.com"
+    domain_env = "bar.com"
+
+    assert universe.determine_domain(domain_client, domain_env) == domain_client
+    assert universe.determine_domain(None, domain_env) == domain_env
+    assert universe.determine_domain(domain_client, None) == domain_client
+    assert universe.determine_domain(None, None) == universe.DEFAULT_UNIVERSE
+
+    with pytest.raises(universe.EmptyUniverseError):
+        universe.determine_domain("", None)
+
+    with pytest.raises(universe.EmptyUniverseError):
+        universe.determine_domain(None, "")
+
+
+def test_compare_domains():
+    fake_domain = "foo.com"
+    another_fake_domain = "bar.com"
+
+    assert universe.compare_domains(universe.DEFAULT_UNIVERSE, _Fake_Credentials())
+    assert universe.compare_domains(fake_domain, _Fake_Credentials(fake_domain))
+
+    with pytest.raises(universe.UniverseMismatchError) as excinfo:
+        universe.compare_domains(
+            universe.DEFAULT_UNIVERSE, _Fake_Credentials(fake_domain)
+        )
+    assert str(excinfo.value).find(universe.DEFAULT_UNIVERSE) >= 0
+    assert str(excinfo.value).find(fake_domain) >= 0
+
+    with pytest.raises(universe.UniverseMismatchError) as excinfo:
+        universe.compare_domains(fake_domain, _Fake_Credentials())
+    assert str(excinfo.value).find(fake_domain) >= 0
+    assert str(excinfo.value).find(universe.DEFAULT_UNIVERSE) >= 0
+
+    with pytest.raises(universe.UniverseMismatchError) as excinfo:
+        universe.compare_domains(fake_domain, _Fake_Credentials(another_fake_domain))
+    assert str(excinfo.value).find(fake_domain) >= 0
+    assert str(excinfo.value).find(another_fake_domain) >= 0
diff --git a/tests/unit/test_version_header.py b/tests/unit/test_version_header.py
new file mode 100644
index 00000000..ea7028e2
--- /dev/null
+++ b/tests/unit/test_version_header.py
@@ -0,0 +1,23 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import pytest
+
+from google.api_core import version_header
+
+
+@pytest.mark.parametrize("version_identifier", ["some_value", ""])
+def test_to_api_version_header(version_identifier):
+    value = version_header.to_api_version_header(version_identifier)
+    assert value == (version_header.API_VERSION_METADATA_KEY, version_identifier)